S 

593 
J7 
1856 


FOR  THE 


ANALYSIS  OF  SOILS,  LIMESTONES, 


AND 


M  A.  N  U  H  E  S. 


BY 


JAMES    F.   W.   JOHNSTON, 

M.A.,   F.K.S8.   L.   &   E.,   AC. 

Author  of  "  Lectures  OQ  Agrrcultural  Chemistry  and  Geology," 
»  »  "  Catechism  of  Agricultural  Chemistry  and  Geology," 

"  The  Chemistry  of  Common  Life,  Ac." 


THIRD    EDITION. 


S.    B.  SHAW, 

PUBLISHER,     OLEVKT,  AND,     OHIO, 
1856. 


HARRIS,    FAIRBANKS   &   CO.,    PRINTERS,    CLEVELAND. 


PREFACE  TO  THE  THIRD  ENGLISH  EDITION. 


THIS  little  work  is  not  intended  to  compete  with  treatises  on 
chemical  analysis,  such  as  those  of  Rose  and  Fresenius,  which  are 
the  text-books  of  the  accomplished  analyst.  Originally  published 
as  an  Appendix  to  my  Lectures  OH  Agricultural  Chemistry  and 
Geology,  it  has  been  much  in  demand  also  in  a  separate  form.  I 
have,  therefore,  given  to  this  third  edition  a  more  widely  practical 
bearing,  by  including  limestones,  clays,  ironstones,  manures,  and 
natural  waters,  among  the  substances  to  be  analysed.  I  have 
briefly  explained,  also,  the  principles  on  which  analysis  by  meas- 
ure is  founded — a  method  which  is  susceptible  of  many  simple 
practical  applications.  The  Instructions  are  as  few  and  simple  as 
the  subject  well  admits  of,  and  the  advancing  student  will  proceed 
from  this  little  manual  to  the  many  larger  works  which  are  within 
his  reach. 

To  the  schoolmaster,  the  farmer,  the  pharmaceutical  chemist 
and  druggist,  the  youthful  student,  and  to  the  rural,  the  training 
or  normal  school,  and  the  agricultural  laboratory,  I  offer  it  as  a 

FIRST   HELP   TO     PRACTICAL  AND   ECONOMICAL   CHEMICAL  ANALYSIS. 

Though  small  in  size,  it  will  materially  aid  them  in  those  chemical 
investigations  which,  in  connection  with  agriculture  and  the  arts, 
are  every  day  becoming  more  sought  for,  and  more  necessary. 
With  a  Tiew  to  easy  reference,  I  have  added  a  copious  Index. 
March  1855. 


AMERICAN    PUBLISHER'S   PREFACE. 


THE  want  in  this  country  of  just  such  a  work  as  Prof.  John- 
ston has  here  given  to  the  world,  there  being  nothing  of  the  kind 
in  the  United  States,  has  induced  the  publisher  to  issue  an  edition 
of  it  for  the  benefit  of  the  farmers  of  America,  in  a  cheap  form. 
The  importance  to  the  Agriculturist  of  a  thorough  knowledge  of 
all  branches  of  his  business,  and  of  the  fundamental  principles 
which  govern  the  development  of  vegetation,  and  its  perfect 
growth,  need  not  be  dwelt  upon.  Every  man  who  understands 
his  own  interests,  desires  a  knowledge  of  everything  which  will 
promote  them,  and  I  have  not  a  remote  doubt  that  a  careful  study 
of  this  little  book,  aided  by  experiments  in  accordance  with  its 
instructions,  will  redound  in  large  benefits  to  the  student.  Few 
and  simple  as  the  Instructions  are,  they  yet  form  one  of  the  most 
valuable  aids  to  the  science  of  Agriculture,  which  have  ever  been 
published. 


CONTENTS. 


CHAT.  PAGE. 

I.    PHYSICAL   PROPERTIES    OF    THE    SOIL,  HOW  DETER- 
MINED, .  ...  .  .  .  .7 

II.  ORGANIC  MATTER  OF  THE  SOIL,  HOW  ESTIMATED,      16 

III.  SALINE  MATTER  OF  THE  SOIL,  HOW  EXAMINED,  .     24 

IV.  ESTIMATION  OF  THE  SALINE  MATTERS — (NATURAL 

WATERS),      .         .         .       ' .     '' .         .         .31 

V.  EARTHY  MATTERS  OF  THE  SOIL (TILE  AND  FIRE 

CLAYS), ..43 

VI.  ANALYSIS  BY  MEASURE (OKES  OF  IRON),  .         .     59 

VII.  GENERAL  REMARKS  ON  THE  ANALYSIS  OF  SOILS 

PRACTICAL  SUGGESTIONS,         .         .         .          .67 

VIII.  ANALYSIS  OF  LIMESTONES  AND  MARLS,       .         .     73 
IX.  ANALYSIS  OF  SALINE  MANURES,  .         .-       .     78 

X.  EXAMINATION  OF  BONE  MANURES,   GUANOS,    AND 

OIL-CAKES,  ,  87 


INSTRUCTIONS 

FOR  THE 

ANALYSIS  OF    SOILS,  LIMESTONES, 
MANURES,  &c. 


CHAPTER  I. 
PHYSICAL    PROPERTIES    OF    THE    SOIL. 

Why  a  soil  should  be  analysed. — Usefulness  of  knowing  the  proportions  of 
lime,  organic  matter,  and  sand  or  clay  inn  soil. — More  refined  inquiries. — 
How  to  select  a  soil  for  examination. — To  determine  the  physical  properties 
of  a  soil;  its  density,  absolute  weight,  proportions  of  sand  and  gravel ;  its 
absorbing  power;  its  power  of  retaining  water ;  rapidity  with  which  it  dries; 
power  of  absorbing  heat  from  the  sun;  and  rapidity  of  cooling.— The  sandy 
deserts. 

§  I.    WHY  A    SOIL  SHOULD  BE  ANALYSED. 

1°.  THE  benefits  to  be  derived  from  the  chemical  exa- 
mination and  analysis  of  a  soil  are  by  many  misunder- 
stood. Some  have  represented  it  as  the  only  sure  guide  to 
successful  cultivation  ;  while  others  have  not  scrupled  to 
pronounce  the  analysis  of  soils  to  be  entirely  useless,  and 
unfitted  to  lead  to  any  profitable  practical  result.  Both, 
of  these  extreme  parties  are  in  error.  For  while  it  is  often 
very  difficult,  from  an  analysis  alone,  to  explain  either  the 


PHYSICAL    PROPERTIES    OF    THE    SOIL. 

past  agricultural  history,  the  present  money  value,  or 
how  best  to  remedy  the  known  defects  of  a  soil,  yet  there 
are  many  practical  points  on  which  analysis  does  throw 
light,  and  modes  of  practical  treatment  which  it  serves  at 
once  either  to  discourage  or  to  recommend. 

2°.  Thus,  on  m  any  accounts,  it  is  desirable  to  know  how 
much  lime  a  soil  contains.  Soils  rich  in  lime  generally 
produce  a  sweet  herbage,  sound  and  nutritious  green  crops, 
and  grain  of  a  full  ear  and  strong  straw.  To  secure  these 
advantages,  the  farmer  is  willing  to  apply  lime  ;  but  the 
land  may  contain  enough  already,  and  to  apply  more 
might  only  be  a  waste  ;  or  it  may  contain  little  or  none, 
and  he  may  be  about  to  apply  too  little.  A  simple 
analysis  settles  difficulties  of  this  kind,  determines  the 
per-centage  of  lime,  and  points  out  what  in  the  circum- 
stances is  best  to  be  done. 

3°.  Again,  the  proportion  of  organic  or  combustible 
matter  in  a  soil  regulates,  in  some  degree,  the  dose  of 
lime  it  is  proper  to  ad'l — the  kind  of  mineral,  vegetable, 
or  other  manure  it  may  be  proper  to  use  upon  it — and  in 
the  case  of  moorish  or  peaty  soils,  how  far  clay  or  sand 
would  be  likely  to  improve  it.  Hence  it  is  desirable  to 
know  what  per-centage  of  organic  matter  a  soil  contains. 

4°.  Again,  a  poor  soil  has  sometimes  much  resemblance 
to  clay,  and  yet,  on  chemical  examination,  proves  to  con- 
sist mainly  of  a  very  fine  sand.  To  ascertain  this,  is  to 
determine  at  once  how  the  soil  may  be  improved.  Or  a 
soil  may  be  found,  upon  analysis,  to  be  too  largely  im- 
pregnated with  oxide  of  iron,  or  to  contain  peculiarly 
noxious  combinations  of  iron,  or  to  be  too  rich  in  common 
salt;  and  each  of  these  results  of  analysis  indicates  to  the 


PHYSICAL    PROPERTIES    OF    THE    SOIL.  9 

skilful  man  the  steps  which  will  most  quickly  or  econo- 
mically bring  the  several  soils  into  a  fertile  condition. 

5°.  These  are  some  of  the  plainer  cases  in  which  useful 
information  may  be  derived  from  comparatively  simple 
analyses  of  soils.  When  the  skill  of  the  analyst  is  suffi- 
ciently refined  to  enable  him  to  detect  or  determine  the 
phosphoric  acid,  the  potash,  the  ammonia,  or  the  nitric 
acid  which  a  soil  contains,  other  conclusions  may  be 
drawn  which  are  not  without  their  practical  value.  It  is 
the  pretended  application  of  such  determinations — made 
hastily  and  without  sufficient  care  or  knowledge,  either 
chemical  or  agricultural — which  have  led  many  to  deny  as 
hastily,  that  any  good  at  all  is  to  be  derived  from  the 
analysis  of  a  soil. — (See  Chap.  VII.) 

§  II. HOW  TO    SELECT    SPECIMENS    OF   SOILS    FOR   ANALYSIS. 

6°.  In  the  same  field,  different  varieties  of  soil  often 
occur  ;  and  some  recommend  that,  in  collecting  a  specimen 
for  analysis,  portions  should  be  taken  from  different  parts 
of  the  field  and  mixed  together,  by  which  an  average 
quality  of  soil  would  be  obtained.  But  this  is  bal  ad- 
vice, when  the  soils  in  different  parts  of  the  field  are 
really  unlike.  Suppose  one  part  of  a  field  to  be  clay,  and 
another  sandy — as  is  often  the  case  in  most  countries — and 
that  an  average  mixture  of  the  two  varieties  of  soil  is  sub- 
mitted to  analysis,  the  result  obtained  will  apply  neither 
to  the  one  part  of  the  field  nor  to  the  other ;  that  is,  it 
will  be  of  little  or  no  practical  value.  In  selecting  a  spe- 
cimen of  soil,  therefore,  one  or  two  pounds  should  be  taken 
from  each  of  four  or  five  parts  of  the  fields  where  the  soil 


10  PHYSICAL   PROPERTIES    OF    THE    SOIL. 

appears  nearly  alike.  These  should  be  well  mixed  together, 
and  dried  in  the  open  air,  or  before  the  fire.  Two  sepa- 
rate pounds  should  then  be  taken  from  the  whole,  for  the 
purpose  of  analysis  ;  or,  if  it  is  to  be  sent  to  a  distance, 
should  be  tied  up  in  clean  strong  paper  ;  or,  what  is  much 
better,  should  be  enclosed  in  clean,  well-corked  bottles. 

§  III. TO     DETERMINE    THE    PHYSICAL   PROPERTIES    OF 

THE  SOIL. 

7°.  Determination  of  the  density  of  the  soil,  or  its  weight 
compared  with  that  of  water. — In  order  to  determine  the 
density  of  the  soil — or  its  specific  gravity,  as  it  is  also 
called — a  portion  of  it  must  be  dried  at  the  temperature 
of  boiling  water  (212°  Fahr.),till  it  ceases  to  lose  weight: 
or  upon  a  piece  of  white  paper,  in  an  oven,  at  a  heat  not 
great  enough  to  render  the  paper  brown.  A  common 
phial  or  other  small  bottle,  perfectly  clean  and  dry,  may 
then  be  taken  and  filled  with  distilled  or  pure  rain-water, 
up  to  a  mark  made  with  a  file  on  the  neck,  and  then  care- 
fully weighed.  Part  of  the  water  may  then  be  poured 
out  of  the  bottle,  and  1000  grains  of  the  dry  soil  intro- 
duced in  its  stead.  The  bottle  must  then  be  well  shaken, 
to  allow  the  air  to  escape  from  the  pores  of  the  soil ; — filled 
up  again  with  water  to  the  mark  on  the  neck,  and  again 
weighed.  The  temperature  of  the  water  should  all  the 
while  be  kept  as  near  to  60°  Fahr.  as  possible.  The 
weight  of  the  soil — divided  by  the  difference  between  the 
weight  of  the  bottle  when  it  contains  the  soil  and  water, 
and  the  sum  of  the  weights  of  the  soil  and  of  the  bottle 
of  water  added  together — gives  the  specific  gravity. 


PrtYSICAL   PROPERTIES    OF    TriE   SOlL.  ll 

Thus,  let  the  bottle  with  water  weigh  2000  grains,  and 
with  water  and  soil  2600,  then — 

Grains. 

The  weight  of  the  bottle  with  water  alone     —  .   .x  .    2000 

The  weight  of  the  dry  soil,          .       .    ,  .    )       .        ...  loOO 

Sum — being  the  weight  which  the  bottle  with  the  soil  ) 
and  water  would  have  had,  could  the  soil  haye  been  /        .  .    3000 

introduced  without  displacing  any  of  the  water, 

But  the  weight  of  the  bottle  fith  soil  and  water  was  .  .    2600 

Difference— being  the  weight  of  water  taken  out  t<  i 

admit  1000  grains  of  dry  soil,  ...  >  400 

Therefore  1000  grains  of  soil  have  the  same  bulk  as  400 
grains  of  water ;  or  the  soil  is  2£  times  heavier  than  water, 
since  YoV  —  2.5  its  specific  gravity. 

8°.  Determination  of  the  absolute  weight. — The  absolute 
weight  of  a  cubic  foot  of  solid  rock  is  obtained  in 
pounds  by  multiplying  its  density  or  specific  gravity  by 
63£ — the  weight  in  pounds  of  a  cubic  foot  of  water.  But 
soils  are  porous,  and  contain  more  or  less  air  in  their 
interstices,  according  as  their  particles  are  more  or  less 
fine,  or  as  they  contain  more  or  less  sand  or  vegetable 
matter.  They  are  not  so  heavy,  therefore,  as  the  solid 
rocks  from  which  the  are  formed.  Fine  sands  are  the 
heaviest,  clays  the  next  in  order,  and  peaty  soils  the  lightest. 
The  simplest  mode  of  determining  the  absolute  weight  of 
a  soil  is  to  weigh  an  exact  imperial  half-pint  of  the  soil  in 
any  state  of  dryness,  when  this  weight,  multiplied  by  1 50, 
will  give  very  nearly  the  weight  of  a  cubic  foot  of  the  soil 
in  that  state. 

9°.  Determination  of  the  relative  proportions  of  gravel, 
sand,  and  clay. — Five  hundred  grains  of  the  dry  soil  may 
be  boiled  in  a  flask,  or  in  a  small  enamelled  iron  pan,  half 
full  of  water,  till  the  particles  are  thoroughly  separated 


12  PHYSICAL   PROPERTIES    OF    THE    SOIL. 

from  each  other.  Being  allowed  to  stand  for  a  couple  of 
minutes,  the  water,  with  the  fine  matter  floating  in  it  may 
be  poured  off  into  another  vessel.  This  may  be  repeated 
several  times,  till  it  appears  that  nothing  but  sand  or 
gravel  remains.  This  sand  and  gravel  is  then  to  be  washed 
completely  out  of  the  flask  or  pan,  dried,  and  weighed . 
Suppose  the  weight  to  be  300  grains,  then  60  per  cent  * 
of  the  soil  is  sand  and  gravel.  The  sand  and  gravel  are 
now  to  be  sifted  through  a  gauze  sieve  more  or  less  fine, 
when  the  gravel  and  coarse  sand  are  separated,  and  may 
be  weighed  and  their  several  proportions  estimated. 

These  separate  portions  of  gravel  and  sand  should  now 
be  moistened  with  water  and  examined  parefully  with  the 
aid  of  a  microscope,  with  the  view  of  ascertaining  if  they 
are  wholly  silicious,  or  if  they  contain  also  fragments  of 
different  kinds  of  rock — sand-stones,  slates,  granites,  traps, 
lime-stones,  or  iron-stones.  A  few  drops  of  strong  muri- 
atic acid  (spirit  of  salt)  should  also  be  added.  The  pre- 
sence of  lime-stone  is  then  shown  more  distinctly  by  an 
effervescence,  which  can  be  readily  perceived  by  the  aid 
of  the  glass — of  peroxide  of  iron,  by  the  brown  colour 
which  the  acid  speedily  assumes — and  of  black  oxide  of 
manganese,  by  a  distinct  smell  of  chlorine,  which  is  easily 
recognised.  In  the  subsequent  description  of  the  soil, 
these  points  should  be  carefully  noted. 

Suppose  the  sand  and  gravel  to  contain  half  its  weight 

of  fine  sand,  then  our  soil  would  consist  of — coarse  sand 

mall  stones  30  per  cent,  fine  sand  30  per  cent,  clay 

and  other  lighter  matters  40  per  cent.     When  the  sand  is 

*  As  500:  300:  :  100  to  60, 


PHYSICAL    PROPERTIES    OF    THE    SOIL.  13 

very  fine,  care  must  be  taken  that  none  of  it  is  washed  off 
and  reckoned  as  clay. 

10°.  Absorbing  power  of  the  soil. — A  thousand  grains  of 
the  soil,  made  perfectly  dry,  as  described  in  7°,  should  be 
crushed  to  powder,  spread  over  a  sheet  of  paper,  exposed 
in  the  open  air  in  ordinary  dry  weather,  shaded  from  the 
sun  for  twelve  or  twenty-four  hours,  and  then  weighed. 
The  increase  of  weight  shows  its  power  of  absorbing  mois- 
ture from  the  air.  If  it  amount  to  1 5  or  20  grains,  it  is 
so  far  an  indication  of  great  agricultural  capabilities. 

11°.  Its  power  of  holding  or  retaining  water. — This  same 
portion  of  soil  may  next  be  put  in  a  funnel  upon  a 
double*  filter,  and  cold  water  poured  upon  it,  drop  by 
drop,  till  the  whole  is  wet  and  the  water  begins  to  trickle 
down  the  neck  of  the  filter.  It  may  now  be  covered  with 
a  piece  of  glass,  and  allowed  to  stand  for  a  few  hours,  occa- 
sionally adding  a  few  drops  of  water,  until  there  remains 
no  doubt  of  the  whole  soil  being  perfectly  soaked.  The 
two  filters  and  the  soil  are  then  to  be  removed  from  the 
funnel,  and  the  filters  opened  and  spread  for  a  few  minutes 
upon  a  linen  cloth,  to  remove  the  drops  of  water  wuich 
adhere  to  the  paper.  The  wet  soil  and  inner  filter  being 
now  put  into  one  scale,  and  the  outer  filter  into  the  other, 
and  the  whole  carefully  balanced,  the  true  weight  of  the 
wet  soil  is  obtained.  Suppose  the  original  thousand 
grains  now  to  weigh  1400,  then  the  soil  is  capable  of 
holding  40  per  cent  of  water,  f 

12°.  Rapidity  with  which  the  soil  dries.- — The  wet  soil 

*  That  is  one  filter  within  another. 

•f  1000  :  400  the  increase  of  weight  as  100  :  40. 


14  PHYSICAL   PROPERTIES    OF    THE    SOIL. 

with  its  filter  may  now  be  spread  out  upon  a  plate,  and 
exposed  to  the  air,  in  what  may  be  considered  the  ordinary 
circumstances  of  temperature  and  moisture  of  the  place, 
for  four,  twelve,  or  twenty-four  hours,  and  the  loss  of 
weight  then  ascertained.  This  will  indicate  the  compara- 
tive rapidity  with  which  such  a  soil  would  dry,  and  the 
consequent  urgent  demand  for  draining,  or  the  contrary. 
As  great  a  proportion  of  the  water  is  said  to  evaporate 
from  a  given  weight  of  silicious  sand  saturated  with  water, 
in  four  hours,  as  from  an  equal  weight  of  pure  clay  in 
eleven,  and  of  peat  in  seventeen  hours — when  these  several 
soils  are  all  placed  in  the  same  circumstances. 

In  making  this  experiment,  a  portion  of  pure  quartz 
sand  or  of  pipe-clay  may  be  employed  for  the  purpose 
of  obtaining  a  comparative  result  as  to  the  rapidity  of 
drying. 

13°.  Power  of  absorbing  heat  from  the  sun. — The  same 
method  may  be  adopted  in  regard  to  the  power  of  the  soil 
to  become  warm  under  the  influence  of  the  sun's  rays. 
Two  small  wooden  boxes,  containing  each  a  layer,  two  or 
three  inches  in  depth,  of  one  of  the  kinds  of  soil  which 
are  to  be  compared,  may  be  exposed  to  the  same  sunshine 
for  the  same  length  of  time,  and  the  heat  they  severally 
acquire  determined  by  a  thermometer,  the  bulb  of  which 
is  buried  a  full  quarter  of  an  inch  beneath  the  surface. 
Soils  are  not  found  to  differ  so  much  in  the  actual  tem- 
perature or  degree  of  warmth  they  are  capable  of  attain- 
ing under  such  circumstances — most  soils,  when  dry,  be- 
coming 20°  or  30°  warmer  than  the  surrounding  air  in 
the  time  of  summer — as  in  the  relative  degree  of  rapidity 
with  which  they  acquire  this  maximum  temperature. 


PHYSICAL   PROPERTIES    OF    THE   SOU..  15 

This  rapidity  depends  very  much  upon  the  darkness  of. 
the  colour  of  the  soil.     When  the  proportion  of  organic 
matter  is  great,  the  soil  is  generally  very  dark  in  colour, 
and  the  absorption  of  heat  from  the  sun  most  rapid. 

But  the  mineral  constituents  of  the  soil  also  influence 
this  quality.  Of  all  the  known  constituents  of  soils,  dry 
quartz  sand  absorbs  heat  most  rapidly.  It  reaches  the 
maximum  temperature,  on  a  sunny  day,  neai-ly  five  times 
sooner  (as  90  to  19 — TiNDALL)lhan  a  similar  surface  of  dry 
gypsum.  To  this  circumstance  is  to  be  ascribed  both 
the  pleasant  warmth  of  the  sand-hills  along  our  sea 
coasts  on  a  summer  day,  and  the  scorching  heats  which 
distinguish  both  air  and  soil  in  regions  of  sandy  desert. 

14°.  Rapidity  of  cooling. — The  above  property  derives 
another  practical  interest  from  its  being  connected  with  a 
corresponding  rapidity  of  cooling.  Dark  soils  cool  most 
rapidly,  and  mists  and  fogs  settle  over  them,  and  dews 
fall  and  moisten  them.  So,  also,  naked  sandy  soils  and 
plains  part  with  their  heat  as  rapidly  as  they  take  it  in. 
Hence  the  chill  nights  which  succeed  the  fiery  noondays 
of  the  African  Sahara— and  hence  the  alternate  heats  and 
chills  which  burn  up  thin  sandy  pastures,  and  make  dark, 
moorish,  or  peaty  lands  unpropitious  to  our  cultivated 
crops. 


CHAPTER  II. 


ORGANIC  MATTER  OF  THE  SOIL. 


Determination  of  the  organic  matter  of  the  soil;  the  proportion  or  per-centage. 
The  humic  and  ulmic  acids. — The  insoluble  vegetable  matter,  or  humu?. 
Other  organic  substances  in  the  soil ;  how  determined. 


15°.  Determination  of  the  per-centage  of  organic  matter, 
The  soil  must  be  thoroughly  dried  in  an  over  or  other- 
wise— in  a  little  sand-bath  for  example,  over  a  lamp  or 
charcoal  fire — at  a  temperature  not  higher  than  from 
250°  to  300°  Fahr.  The  humic  and  ulmic  acids  of  soils* 
will  bear  the  latter  temperature  without  change.  An 
accurately  weighed  portion  (100  to  200  grains)  must 
then  be  burned  in  the  open  air,  till  all  the  blackness 
disappears.  This  is  best  done  in  a  small  platinum  capsule, 
over  an  argand,  spirit,  or  gas  lamp.  The  loss  indicates 
the  total  weight  of  organic  matter  present.  It  is  scarcely 
ever  possible,  however,  to  render  soils  absolutely  dry, 
without  raising  them  to  a  temperature  so  high  as  to 
char  the  organic  matter  present.  Hence  the  weight  of 
the  organic  matter,  as  determined  from  the  loss,  will 
always  somewhat  exceed  the  truth  ;  the  water  which  still 

•  See  the  author's  Lerlures  on  Agricultural  Chemislry  and  Geology,  2d  edition  k 
p.  71 ;  or  his  Elements,  6th  edition,  p.  21. 


ORGANIC   MATTER   OF    THE    SOIL.  17 

I 

remains  in  the  soil  being  driven  off  along  with  the  organic 
matter,  when  the  soil  is  heated  to  redness.  This  excess, 
also,  will  in  general  be  greater  in  proportion  to  the  quan- 
tity of  clay  in  the  soil,  since  this  is  the  ingredient  of  most 
soils  from  which  the  water  is  expelled  with  the  greatest 
difficulty.— (See  under  18°  c.) 

16°.  Determination  of  the  humicand  ulmic  acids. — These 
acids,  whether  merely  mixed  with  the  soil,  or  combined  with 
some  of  the  lime  and  alumina  it  contains,  are  extracted 
by  boiling  with  a  solution  of  the  common  crystalised 
soda  of  the  shops.  Into  about  two  ounces  by  measure 
of  a  saturated  solution  of  this  soda,  contained  in  a  flask, 
200  or  300  grains  of  soil,  previously  reduced  to  coarse 
powder,  are  introduced,  an  equal  bulk  of  water  added, 
and  the  whole  boiled  or  digested  on  the  sand-bath,  with 
occasional  shaking  for  an  hour  or  two.  The  flask  is  then 
removed  from  the  fire,  filled  up  with  water,  well  shaken, 
again  boiled,  and  the  particles  of  soil  afterwards  allowed 
to  subside.  The  clear  liquid  is  then  poured  off.  If  it  has  a 
brown  colour,  it  has  taken  up  some  humic  or  ulmic  acid. 
In  this  case,  the  process  must  be  repeated  once  or  twice 
with  fresh  portions  of  the  soda  solution,  till  the  soluble 
organic  matter  appears,  by  the  pale  colour  of  the  last 
solution  to  be  altogether  taken  up.  These  coloured 
solutions  are  then  to  be  mixed  and  filtered.  This  filter- 
ing generally  occupies  considerable  time,  the  humic  and 
ulmic  acids  clogging  up  the  pores  of  the  filter  in  a 
remarkable  manner,  and  permitting  the  liquid  to  pass 
through  sometimes  with  extreme  slowness. 

When  filtered,  muriatic  acid  is  to  be  slowly  added  to 
the  coloured  liquid — which  should  be  kept  in  motion  by 
2 


18  ORGANIC   MATTER   OP   THE   SOIL. 

a  glass  rod — till  effervescence  ceases,  and  the  whole  has 
become  distinctly  sour.  On  being  set  aside,  the  mixed 
ulmic  and  humic  acids  fall  in  brown  flocks.  A  filter  is 
now  to  be  dried  and  carefully  weighed,*  the  liquid  fil- 
tered through  it,  and  the  acids  thus  collected.  They 
must  be  washed  on  the  filter  with  pure  water — rendered 
very  slightly  sour  by  muriatic  acidf — till  all  the  soda  is 
separated. £  The  filter  with  its  contents  is  then  to  be 
dried  at  250°  Fahr.,  till  it  ceases  to  lose  weight.  The 
final  weight,  when  the  known  weight  of  the  filter  is 
deducted  from  it,  gives  the  quantity  of  humic  and  ulmic 
acids  contained  in  the  portion  of  soil  submitted  to  exa- 
mination. As  it  is  rarely  possible  to  wash  these  acids 
perfectly  upon  the  filter,  rigorous  accuracy  requires  that 
the  filter  and  acids  should  be  burned  after  being  weighed, 
and  the  weight  of  ash  left,  minus  the  known  weight  of 
ash  left  by  the  filter,§  deducted  from  that  of  the  acids 

•  This  is  best  effected  by  putting  the  filter  into  a  small  covered  porcelain  cruci- 
ble of  known  weight,  and  heating  it  for  ten  minutes  over  a  lamp  or  otherwise, 
at  a  temperature  which  just  does  not  discolour  the  paper,  allowing  then  the 
crucible  to  cool  under  cover,  and  when  cold  weighing  it.  The  increase  above  the 
known  weight  of  the  crucible  is  that  of  the  filter,  which,  besides  being  recorded 
in  the  experiment-book,  should  also  be  marked  in  several  places  on  the  edge  of 
the  filter  with  a  black-lead  pencil. 

-;•  This  is  to  prevent  the  humic  acid  from  passing  through  the  filter,  which  it  in 
rery  apt  to  do,  when  the  saline  matter  is  neatly  washed  out  of  it. 

\  This  is  ascertained  by  collecting  a  few  drops  of  what  is  passing  through 
upon  a  slip  of  clean  glass  or  of  platinum  foil,  and  drying  them  over  the  lamp, 
when,  if  a  perceptible  stain  or  spot  is  left,  the  subst&nce  it  not  sufficiently  washed. 

|  The  ash  left  by  the  paper  employed  for  filters  should  always  be  known.  This 
is  ascertained,  once  for  all,  by  drying  a  quantity  of  it  in  the  way  described  in  the 
previous  note,  weighing  it  in  this  dry  state,  burning  it,  and  again  weighing  the 
ash  that  is  left.  In  good  filtering  paper,  the  ash  ought  not  to  exceed  one  percent. 


ORGANIC   MATTER   OF   THE   SOIL.  19 

as  previously  determined.  It  is  to  be  observed  here  that 
by  this,  which  is  really  the  only  available  method  we 
possess  of  estimating  the  humic  and  ulmic  acids,  a  certain 
amount  of  loss  arises  from  their  not  being  wholly  insoluble, 
the  acid  liquid  which  passes  through  the  filter  being 
always  more  or  less  of  a  brown  colour.* 

The  two  acids  thus  estimated  occur  in  soils  mixed 
together  in  various  undetermined  proportions.  It  is  not 
easy  to  separate  them  from  each  other,  and  no  known 
practical  good  would  result  from  a  rigorous  determination 
of  the  proportions  of  each. 

17°.  Determination  of  the  insoluble  vegetable  matter  or 
humus. — Many  soils,  after  this  treatment  with  carbonate 
of  soda,  are  still  more  or  less  of  a  brown  colour,  evidently 
due  to  the  presence  of  other  organic  matter.  To  separate 
this,  it  is  recommended  to  boil  the  soil,  which  has  been 
treated  with  carbonate  of  soda,  and  which  we  suppose 
still  to  remain  in  the  flask,  with  a  solution  of  caustic 
potash,  repeated,  if  necessary,  as  in  the  case  of  the  soda 
solution.  By  this  boiling,  the  vegetable  matter,  which 
was  insoluble  in  the  carbonate  of  soda  is  changed  in 
chemical  constitution,  and  dissolves  in  the  caustic  potash, 
giving  a  brown  solution.  From  this  it  may  be  separated 
in  brown  flocks  by  the  addition  of  muriatic  acid,  and  then 
collected  and  weighed  as  above  described. 

In  some  soils,  also,  distinct  portions  of  scarcely  altered 

•The  portion  which  thus  remains  in  solution  may  be  precipitated  by  adding  a 
imall  quantity  of  a  solution  of  alum,  and  afterwards  pouring  in  ammonia  in 
excess.  The  alumina  falls  coloured  by  the  organic  matter,  and  after  being  col- 
lected on  a  filter,  washed  and  dried,  the  weight  of  organic  matter  in  the  precipi- 
tate may  be  determined  approximately  as  described  under  15*. 


20  ORGANIC    MATTER    OF    THE    SOIL. 

vegetable  fibre — such  as  portions  of  roots,  &c.— are  pre- 
sent, and  may  be  separated,  mechanically  dried,  and 
weighed. 

1 8°.  Of  other  organic  substances  present  in  the  *oi/.— The 
sum  of  the  weights  of  the  above  substances,  deducted  from 
the  whole  weight  of  organic  matter,  as  determined  by 
burning,  gives  that  of  the  other  organic  substances  present 
in  the  soil.  The  quantity  of  these  is  in  general  compara- 
tively small ;  and  unless  they  are  soluble  in  water,  there 
is  no  easy  method  of  separating  them  and  determining 
their  weight.  The  following  two  methods,  however,  may 
be  resorted  to  : — 

a.  Half  a  pound  or  more  of  the  moist  soil  may  be 
boiled  with  two  separate  pints  of  distilled  water,  the 
liquid  filtered  and  evaporated  to  a  small  bulk.  From 
clay  soils,  when  thus  boiled  with  water,  the  fine  particles 
do  not  readily  subside.  Sometimes,  after  standing  for 
several  days,  the  water  is  still  muddy,  and  passes 
muddy  through  the  filter  ;  but  after  being  evaporated,  as 
above  recommended,  to  a  small  bulk,  most  of  the  fine 
clayey  matter  remains  on  the  paper  when  it  is  again  fil- 
tered. As  soon  as  it  has  thus  passed  through  clear,  the 
liquid  may  be  evaporated  to  perfect  dryness  at  250°  Fahr. 
and  weighed.  Being  now  treated  with  water — a  portion 
will  be  dissolved — this  must  be  poured  off,  and  the  in- 
soluble remainder  again  perfectly  dried  at  250°  Fahr., 
and  weighed.  If  this  remainder  be  now  heated  to  red- 

o 

ness  in  the  air,  any  organic  matter  it  contains  will  be 
burned  off,  and  the  weight  of  this  organic  matter  will 
be  indicated  by  the  loss  on  again  weighing.  This  loss 
may  be  considered  as  humic,  ulmic,  or  some  other  acid 


ORGANIC    MATTER   OP   THE   SOIL.  21 

rendered  insoluble  by  the  drying  at  250.*  It  does 
not  require  to  be  added  to  the  weight  of  humic  acid 
already  determined  (16°)  because  in  that  experiment 
a  portion  of  soil  was  employed  which  had  not  been 
boiled  in  water,  and  from  which,  therefore,  the  carbo- 
nate of  soda  would  not  at  once  extract  all  the  humic  and 
other  acids.  The  present  experiment  need  only  be  made 
when  it  is  desirable  to  ascertain  what  weight  of  acid 
organic  matter  a  soil  contains  in  a  state  in  which  it  is 
soluble  in  water.  Where  carbonate  of  ammonia,  of  potash, 
or  of  soda  is  present  in  the  soil,  this  quantity  may  be 
very  considerable,  and  may  exercise  an  important  influ- 
ence upon  vegetation. 

b.  That  which  was  taken  up  by  water  from  the  dried  resi- 
duum is  again  to  be  evaporated  to  dryness  dried  at  212°, 
weighed,  and  burned  at  a  low  red  heat.  The  loss  is  organic 
matter,  and  may  have  been  crenic  or  apocrenic,  or  some 
other  of  the  organic  acids  which  are  formed  in  soils,  and 
the  compounds  of  which,  with  lime,  alumina,  and  protoxide 
of  iron,  are  soluble  in  water.  If  any  little  sparkling  or 
burning,  like  match-paper,  be  observed  during  this  heating 
to  redness,  it  may  be  considered  as  an  indication  of  the 
presence  of  nitric  acid — in  the  form  of  nitrate  of  potash, 
soda,  or  lime.  In  this  case  the  loss  by  burning  will  slightly 
exceed  the  true  amount  of  organic  matter  present,  owing 
to  the  decomposition  and  escape  of  the  nitric  acid  also. 

•  »  It  may,  for  example,  consist  in  part  ofgeic  or  spocrenic  acids  (see  Lectures  or 
Eltmentt)  especially  if  there  be  iron  in  the  ash  which  remains..  Where  gypsum 
is  present  in  the  insoluble  portion,  which  is  not  unfrequently  the  case,  the  loss 
will  be  partly  water— since  gypsum,  after  being  dried  at  250",  loses  gtill  about  21 
per  cent  of  water  when  heated  to  redness. 


22  ORGANIC   MATTER   OF    THE    SOIL. 

The  mode  of  estimating  the  quantity  of  this  acid,  when  it 
is  present  in  any  sensible  proportion,  will  be  hereafter 
described. 

c.  The  caustic  potash  employed  to  dissolve  the  insol- 
uble humus  (17°)  takes  up  also  any  alumina  which  may 
have  been  in  combination  with  the  humic  or  ulmic  acids, 
or  may  stilll  remain  united  to  the  geic,  crenic,  mudesous, 
or  other  organic  acids.  When  the  solution  is  filtered,  and 
the  humic  and  ulmic  acids  are  separated  from  it  by  the 
addition  of  muriatic  acid  till  the  liquid  has  a  distinctly 
sour  taste,  this  alumina,  and  the  acids  with  which  it  is 
in  combination,  still  remain  in  solution.  After  the  brown 
flocks  of  humic  acid,  however,  are  collected  on  the  filter, 
the  alumina  may  be  thrown  down  from  the  filtered  solu- 
tion by  adding  caustic  ammonia  to  the  sour  liquid,  until 
it  has  a  distinctly  ammoniacal  smell.  The  light  precipi- 
tate which  falls  must  be  collected  on  a  filter,  and  washed 
with  hot  water  till  the  potash  is  as  completely  separated 
from  it  as  possible.  It  is  then  to  be  dried  at  300°  F. , 
heated  for  some  time  in  a  close  crucible  over  the  lamp,  at 
a  temperature  which  begins  to  discolour  it,  and  weighed. 
Being  now  burned  in  the  air  till  it  is  quite  white,  and 
again  weighed,  the  last  loss  may  be  considered  as  mude- 
sous, or  some  similar  organic  acid. 

The  reason  why  this  second  method  of  drying  over  the 
lamp  is  here  recommended,  is  that  alumina  and  nearly  all 
its  compounds  part  with  their  water  with  great  difficulty  ; 
and  even  with  the  precautions  above  prescribed,  it  is  very 
likely  that  a  larger  per-centage  of  organic  matter  may  be 
indicated  by  this  experiment  than  in  reality  exists  in 
the  alumina  collected  and  dried.  The  check  which 


ORGANIC    MAfTER   OP   THE   SOIL.  23 

the  accurate  experimenter  has  upon  all  these  deter- 
minations is  this,  that  the  sum  of  the  several  weights  of 
the  humic  and  ulmic  acids,  the  insoluble  humus,  the  vege- 
table fibre — and  of  the  crenic  and  mudesous  acids,  if  pre- 
sent— should  be  somewhat  less  than  that  of  the  whole 
combustible  organic  mater,  as  determined  by  burning  the 
dry  soil  in  the  open  air  (15°).  This  quantity  we  have 
seen  to  be  in  most  cases  greater  than  the  truth,  because 
any  remaining  water,  or  any  nitric  acid  the  soil  may  con- 
tain, is  at  the  same  time  driven  off. 

I  may  further  remark  upon  this  subject,  that  the  quan- 
tity of  alumina  thus  dissolved  by  the  caustic  potash,  is  in 
most  soils  very  small,  and  the  quantity  of  organic  matter 
by  which  it  is  accompanied  in  many  cases  so  minute,  that 
the  determination  of  it  may  be  considered  as  a  matter  of 
curiosity,  rather  than  one  of  practical  importance. 


CHAPTER  III. 

SALINE   MATTER    OF    THE   SOIL. 

Qualitative  determination  of  the  matters  soluble  in  water. — To  test  for  sulphuric 
acid,  for  chlorine,  for  alumina,  magnesia,  and  the  oxides  of  iron  and  manga- 
nese, for  lime,  for  potash  and  soda,  for  ammonia  and  for  phosphoric  acid,  by 
different  methods. 

19°.  WITH  a  view  to  determine  the  nature  of  the  soluble 
saline  matter  in  the  soil,  a  preliminary  experiment  must 
be  made.  An  unweighed  portion  must  be  introduced 
into  five  or  six  ounces  of  boiling  distilled  water*  in  a 
flask  and  kept  at  a  boiling  temperature,  with  occasional 
shaking  for  a  quarter  of  an  hour.  It-may  then  be  allowed 
to  subside,  after  which  the  liquid  is  to  be  filtered  till  it 
passes  through  clear.  This  is  to  be  repeated  once  or 
twice,  and  the  several  liquids  mixed.  The  solution  is  then 
to  be  tested  in  the  following  manner  : 

Small  separate  portions  are  to  be  put  into  so  many 
clean  wine-glasses  or  test-tubes,  and  the  effect  produced 
upon  these  by  different  chemical  substances  carefully 
noted.  If  with  a  few  drops  of — 

20°.  Nitrate  of  baryta,  it  gives  a  white  powdery  preci- 
pitate, which  does  not  disappear  on  the  addition  of  nitric 

•  In  all  analytical  operation*  in  which  the  uee  of  water  is  spoken  of,  it  must 
bo  understood  that  pure  distilled  water  is  meant. 


SALINE    MATTER    OF   THE   SOIL.  25 

or  muriatic  acid,  the  solution  contains  sulphuric  acid.  If 
the  precipitate  does  disappear  on  adding  the  acid,  it  con- 
tains carbonic  acid.  In  this  latter  case,  the  liquid — if 
concentrated  to  a  small  bulk — will  also  effervesce  on  the 
addition  of  either  of  the  acids  above  mentioned.* 

21  °.  If  with  nitrate  of  silver  it  gives  a  white  curdy  pre- 
cipitate, insoluble  in  pure  nitric  acid,  and  speedily  be- 
coming purple  in  the  sun,  it  may  be  presumed  to  contain 
chlorine. 

22°.  If  with  caustic  ammonia  it  gives  a  pure  white 
gelatinous  precipitate,  it  contains  either  alumina,  or  mag- 
nesia, or  both.  In  this  case,  muriatic  acid  must  be  added 
till  the  precipitate  disappears,  and  the  solution  is  dis- 
tinctly acid.  If  on  the  addition  of  ammonia  again,  and 
in  excess,  the  precipitate  reappears  undiminished  in 
quantity,  it  contains  alumina  only.  If  it  be  distinctly 
less  in  quantity,  we  may  infer  the  presence  of  both  mag- 
nesia and  alumina ;  and  if  no  precipitate  now  appears, 
that  it  contains  magnesia  only.  If  a  large  quantity  of 
magnesia  be  present,  it  may  be  necessary  to  re-dissolve 
the  precipitate  thrown  down  by  ammonia,  and  to  make 
the  solution  acid  a  second  time  before — on  the  re-addition 
of  ammonia — the  precipitate  will  entirely  disappear. 

23°.  If  the  precipitate,  by  ammonia,  have  more  or  less 
of  a  brown  colour,  the  presence  of  iron,  and  perhaps  man~ 
ganese,  may  be  inferred.  If,  after  re-dissolving  and  adding 
ammonia  a  second  time,  the  colour  of  the  precipitate  has 

*  The  leained  reader  will  understand  why,  for  the  sake  of  simplicity,  I  take  no 
notice  of  substances  not  likely  to  be  present  In  the  soil— as,  for  example,  baryta, 
which  would  here  be  thrown  down  along  witk  the  lime,  or  of  oxalic  acid,  which, 
equally  with  the  sulphuric  or  carbonic  acid,  would  give  a  white  precipitate  with 
nitrate  of  baryta. 


26  SALINE    MATTER   OF    THE    SOIL. 

disappeared,  it  has  been  due  to  manganese  only;  if  it  still 
continue  brown,  it  is  owing  chiefly  or  altogether  to  the 
presence  of  oxide  of  iron.  If  the  colour  of  the  precipitate 
by  ammonia,  be  very  dark,  it  consists  almost  entirely  of 
oxide  of  iron,  and  may  contain  little  or  no  alumina  ;  when 
it  is  only  more  or  less  brown,  the  presence  of  both  alumina 
and  oxide  of  iron  may  with  certainty  be  inferred. 

24°.  a.  If,  after  the  first  addition  of  ammonia,  the  solu- 
tion be  filtered  to  separate  the  alumina,  the  oxides  of  iron 
and  manganese,  and  the  magnesia  that  may  be  thrown 
down — if  then,  with  oxalate  of  ammonia,  it  gives  either 
immediately.or  after  a  time,a  white  cloud,which  gradually 
falls  to  the  bottom  in  the  form  of  a  white  powder,  it  con- 
tains lime.  The  greater  and  the  more  speedy  the  milki- 
ness,  the  larger  the  quantity  of  lime  may  be  presumed  to 
be.  Of  course,  if  ammonia  produces  no  change  in  the 
liquid,  the  oxalate  of  ammonia  may  be  added  at  once, 
without  the  previous  filtration,  which  is  required  to  sepa- 
rate oxide  of  iron,  alumina,  or  magnesia. 

b.  If  oxalate  of  ammonia  be  thus  added  till  all  the  lime 
falls,  and  the  liquid  be  again  filtered,  evaporated  to  dry- 
ness,  and  then  heated  to  incipient  redness  in  the  air,  till 
the  excess  of  oxalate  of  ammonia  is  destroyed  and  driven 
off — and  if  a  soluble  residue  then  remain,*  it  is  probable 
that  potash  or  soda,  or  both,  are  present. 

c.  If,  on  dissolving  this  residue  in  a  little  water,  the 
addition  of  a  few  drops  of  a  solution  of  tartaric  acid  to 
it  produce   a  deposit   of  small  colourless   crystals    (of 
cream  of  tartar),  or  if  a  drop  of  a  solution  of  bi-chloride 

•  Xot  prectp'.tated  from  its  solution  by  ammonia,  for  if  so  precipitated,  it  if 
partly  at  least  chloride  of  magnesium. 


SALINE    MATTER    OF    THE    SOIL. 

of  platinum  produce  in  a  short  time  a  yellow  powdery 
precipitate,  it  contains  potash.  If  no  precipitate  is  pro- 
duced by  either  of  these-r-re-agents,  as  they  are  called — 
the  presence  of  soda  may  be  inferred.  If  a  yellow  pre- 
cipitate, containing  potash  and  platinum,  be  formed,  it 
is  to  be  separated  by  a  filter,  and  the  filtered  solution, 
after  being  treated  with  sulphuretted  hydrogen  and  again 
filtered,  to  separate  the  excess  of  bi-chloride  of  platinum, 
is  to  be  evaporated  to  dryness.  If,  then,  a  soluble  saline 
residue  still  remain,  the  solution  contains  soda  as  well  as 
potash. 

It  is  to  be  observed,  that  some  magnesia,  if  present, 
may  accompany  the  potash  and  soda  through  these  several 
processes.  After  the  separation  of  the  potash,  a  little 
caustic  ammonia  will  detect  the  presence  of  magnesia  ;  but 
it  will  rarely  be  found  so  far  to  interfere  with  this  preli- 
minary examination  as  to  prevent  the  experimenter  from 
arriving  at  correct  results. — (See  37°), 

25°.  If  the  addition  of  bi-chloride  of  platinum  to  the 
solution — filtered  from  the  soil  and  evaporated  to  a  small 
bulk — give  a  yellow  precipitate,  it  contains  either  potash 
or  ammonia.  If,  when  collected  on  the  filter,  dried,  and 
heated  to  bright  redness  in  the  air,  white  fumes  are  given 
off  by  this  yellow  precipitate,  and  only  a  spongy  mass  of 
metallic  platinum  remains  behind,  the  solution  contains 
ammonia  only.  If,  along  with  the  platinum,  there  remains 
after  the  heating,  a  portion  of  a  substance  which  is  soluble 
in  water,  has  a  taste  like  that  of  common  salt,  and  gives 
again  a  yellow  precipitate  with  bi-chloride  of  platinum,  it 
contains  potash, — and  if  the  spongy  platinum  contained  in 
the  burned'mass,  after  prolonged  heating,  amount  to  more 


28  SALINE    MATTER    OF    THE    SOIL. 

than  57  per  cent  of  the  weight  of  the  yellow  precipitate 
collected,  or  if  it  be  to  the  matter  soluble  in  water  in  a 
higher  proportion  than  that  of  4  to  3,  the  solution  con- 
tains both  potash  and  ammonia. 

26°.  The  presence  of  ammonia  among  the  substances 
extracted  by  water  from  the  soil  may  also  be  detected  by 
evaporating  the  liquid  to  a  small  bulk,  or  to  perfect  dry- 
ness  on  the  water-bath,  and  then  adding  a  few  drops  of  a 
solution  of  caustic  potash.  The  smell  of  ammonia,  if  pre- 
sent, becomes  immediately  perceptible  ;  or  if  in  too  small 
quantity  to  be  detected  by  the  smell,  it  will,  if  present, 
restore  the  blue  colour  to  reddened  litmus  paper.  This 
experiment  is  best  made  in  a  small  tube. 

27°.  If,  when  the  solution,  obtained  directly  from  the 
soil,  is  evaporated  to  dryness,  and  the  residue  heated  to 
redness  in  the  air,  a  deflagration  or  burning  like  match - 
paper  be  observed,  nitric  acid  is  present.  Or,  if  the  dry 
mass,  when  put  into  a  test-tube  with  a  little  muriatic 
acid,  evolves  distinct  red  fumes  on  being  heated,  or  enables 
the  muriatic  acid  to  dissolve  gold-dust,  and  form  a  yellow 
solution ;  or,  if  to  a  colourless  solution  of  green  vitriol 
(sulphate  of  iron),  introduced  into  the  tube  along  with  the 
muriatic  acid,  it  imparts  more  or  less  of  a  brown  colour — 
in  any  of  these  cases  the  presence  of  nitric  acid  may  with 
certainty  be  inferred.  It  will  be  only  on  rare  occasions, 
however,  that  salts,  so  soluble  as  the  nitrates,  will  be 
found  in  sensible  quantity  in  the  small  portion  of  a  soil 
likely  to  be  employed  in  these  preliminary  experiments. 
—(See  69°.) 

28°  a.  If  ammonia  throw  down  nothing  from  the  solu- 
tion, and  if  nothing  fall  when  a  few  drops  of  a  solution 


. 

SALINE   MATTER  OF   THE   SOIL.  29 

of  chloride  of  calcium  is  added,  no  phosphoric  acid   is 
present. 

b.  Or,  if  nothing  be  thrown  down  by  ammonia,  the  solu- 
tion may  be  evaporated  to  a  very  small  bulk,    rendered 
acid  by  the  addition  of  nitric  acid,  and  then  dropped  into 
a  solution   of  molybdate  of  ammonia,  prepared  as  de- 
scribed in  40°  a.  If  any  trace  of  a  yellow  precipitate  now 
fall,  phosphoric  acid  is  present. 

c.  But  if  ammonia  cause  a  precipitate  (see  22°),  and 
after  this  is  separated  by  the  filter  nothing  farther  falls 
on  adding  the  chloride  of  calcium  as  above  described  (a), 
the  phosphoric  acid,  if  any  is  present,  is  contained  in  the 
precipitate  thrown  down  by  ammonia.     Let  this,   after 
being  well  washed  on  a  filter  with  distilled  water,  be  dis- 
solved off  with  a  little  diluted  nitric  acid.     This  solution, 
reduced  if  necessary  to  a  small  bulk,  is  to  be  dropped  into 
a  solution  of  molybdate  of  ammonia,  as  above  described 
(I),  and  thus  tested  for  phosphoric  acid. 

d.  Or,  if  the  precipitate  thrown  down  by  ammonia  be 
wholly  or  in  part  insoluble  in  pure  acetic  acid  in  the  cold, 
that  which  is  undissolved  probably  contains  phosphoric 
acid  in  combination  with  peroxide  of  iron,  or  alumina,  or 
both,  and  may  be  farther  tested,  if  thought  necessary,  with 
molybdate  of  ammonia.     But  if  cold  acetic  acid  dissolve 
the  whole,  it  may  be  inferred  that  no  phosphoric  acid  is 
present  in  the  precipitate  thrown  down  by  ammonia.* 

I  have  been  thus  particular  in  describing  the  methods 

*  This  latter  sentence  is  true  only  in  the  case  of  a  precipitate  obtained  by 
means  of  ammonia  from  a  solution  which,  like  that  of  a  soil,  always  contains 
iron  and  alumina.  If  a  solution  of  phosphate  of  lime  (bone  earth),  or  of  phos- 
phate of  magnesia  in  muriatic  acid,  for  example,  be  treated  with  ammonia  in  ex- 
cess, a  white  precipitate  will  fall  which  does  contain  phosphoric  acid,  and  yet 


30  SALINE   MATTER   OF   THE   SOIL. 

of  detecting  phosphoric  acid  in  the  soil,  both  because  it  has 
always  been  one  of  the  most  difficult  substances  to  detect 
when  present  only  in  minute  quantity,  and  because  it  is 
also- one  of  the  most  important  ingredients  of  a  soil. 

29°.  If,  when  the  solution  is  evaporated  to  dryness  on 
the  water-bath,  the  dry  residue  moistened  with  muriatic 
acid  and  treated  with  water — if  then  a  light  flocky  matter 
be  separated,  which,  when  collected  and  heated  to  red- 
ness, only  burns  white  and  does  not  disappear,  it  contains 
silica.' 


These  preliminary  trials  being  made,  notes  should  be 
kept  of  all  the  appearances  presented.  The  arranging 
of  the  method  and  order  to  be  adopted  for  separating 
from  one  another,  and  for  estimating  the  weight  of  each  of 
the  substances,  will  depend  upon  the  number  and  nature 
of  those  which  the  solution  has  been  found  actually  to 
contain. 

It  is  to  be  observed  that  the  methods  above  described, 
as  suited  for  the  examination  of  the  saline  solutions  ob- 
tained from  a  soil,  are  equally  applicable  to  the  examina- 
tion of  any  other  saline  solution,  whether  natural  or  arti- 
ficial. 

dissolves  readily  in  acetic  acid.  Bat  if,  before  adding  ammonia  to  the  muriatic 
acid  solution  of  the  phosphate,  a  few  drops  of  a  solution  of  sulphate  of  peroxide 
of  iron  be  poured  into  it,  then  ammonia  throws  down  a  precipitate  of  a  brownish 
colour,  which  is  not  wholly  dissolved  by  acetic  acid.  The  peroxide  of  iron  which 
was  added  has  united  with  phosphoric  acid,  and  formed  a  combination  which  is 
insoluble  in  ace^icAcid. 


CHAPTER  IV. 

ESTIMATION  OF  THE  SALINE  MATTERS. 

Quantitative  determination  of  the  several  substances  dissolved  out  by  water. — Esti- 
mation of  the  sulphuric  acid,  of  the  chlorine,  of  the  lime,  of  the  oxide  of 
iron,  of  the  alumina,  and  of  the  manganese.— Different  methods  of  estimating 
the  magnesia. — Estimation  of  the  potash,  soda,  and  ammonia. —  Difficulties 
attending  the  estimation  of  the  phosphoric  acid.— Method  by  molybdate  of 
ammonia. — Examination  of  natural  waters. 

30°.  The  quantity  of  soluble  saline  matter  extracted 
from  a  moderate  quantity  of  any  of  our  soils  is  rarely  so 
great  as  to  admit  of  a  rigorous  analysis  being  made,  and 
the  preceding  determination  of  the  kind  of  substances 
it  contains  will  be  in  most  cases  sufficient.  Cases  may 
occur,  however,  in  which  much  saline  matter  may  be 
obtained  by  treating  the  soil  with  water. — (See  69°.)  It 
will  be  proper,  therefore,  briefly  to  state  the  methods  by 
which  the  respective  quantities  of  each  constituent  may 
be  accurately  determined. 

31°.  Estimation  of  the  sulphuric  acid. — The  solution 
being  gently  warmed,  a  few  drops  of  nitric  acid  are  to  be 
added  until  it  becomes  slightly  sour,  and  any  carbonic 
acid  that  may  be  present  is  expelled.  Nitrate  of  baryta 
is  then  to  be  added  to  the  solution  as  long  as  anything 
falls.  The  white  precipitate,  which  is  sulphate  of 


32  ESTIMATION   OF    THE   SALINE   MATTERS. 

baryta,  is  then  to  be  collected  on  a  weighed  filter,  well 
washed  with  distilled  water,  dried  over  boiling  water,  cr 
at  212°Fahr.,  as  long  as  it  loses  weight,  and  then  weighed. 
The  weight  of  the  filter  being  deducted,*  every  100  grains 
of  the  dry  powder  are  equal  to  34.31  grains  of  sulphuric 
acid. 

32°.  Estimation  of  the  chlorine. — The  solution  of  nitrate 
of  silver  must  be  added  as  long  as  any  precipitate  falls, 
the  precipitate  then  washed,  dried  at  212°  Fahr.,  and 
weighed  as  before.  Every  100  grains  of  chloride  of  silver 
indicate  24.72  grains  of  chlorine,  or  40.56  grains  of  com- 
mon salt. 

33°.  Estimation  of  the  lime. — A  little  diluted  muriatic 
acid  being  now  added  to  throw  down  the  excess  of  silver, 
and  a  little  sulphuric  acid  to  separate  the  excess  of 
baryta  added  in  the  former  operations,  and  the  precipi- 
tates caused  by  these  acids  separated  by  filtration, 
caustic  ammonia  is  to  be  poured  in,  till  the  solution  is 
distinctly  alkaline.  If  no  precipitate  fall,  oxalate  of 
ammonia  is  to  be  added  as  long  as  any  white  powder 
appears  to  Be  produced.  The  solution  must  then  be  left 
to  stand  over-night,  that  the  whole  of  the  lime  may 
separate  ;  the  white  powder  afterwards  collected  on  a 
filter,  washed,  dried,  and  burned  with  the  filter  at  a  low 
red  heat.  The  grey  powder  obtained  is  carbonate  of 
lime,  every  100  grains  of  which — the  ash  of  the  filter 
being  deducted — contain  44  grains  of  lime. 

To  be  quite  sure  that  the  whole  of  the  lime  is  thrown 

•  Or  the  whole  may  be  heated  to  redness  in  the  air,  and  the  filter  burned 
»w»y.  In  this  case,  the  weight  of  aah  left  by  the  paper  must  be  ascertained  by 
previous  trials,  and  the  due  proportion  deducted  from  the  weight  of  the  sulphate 
(p.  18,  n»te.) 


ESTIMATION   OF   THE   SALINE   MATTEKS.  33 

down,  it  is  proper  to  add  a  few  additional  drops  of 
oxalate  of  ammonia  to  the  clear  solution  before  filtering 
it.  If  no  milkiness  is  produced  after  half  an  hour  or  an 
hour,  the  lime  has  all  fallen. 

34° .  Estimation  of  the  peroxide  of  iron. — But  if  a  precipi- 
tate fall  on  the  addition  of  ammonia,  as  above  prescribed, 
the  solution  may  contain  magnesia,  alumina,  and  the 
oxides  of  iron  and  manganese.  In  this  case  the  precipi- 
tate is  to  be  re-dissolved  by  the  addition  of  muriatic  acid 
to  the  solution  till  it  is  distinctly  acid,  and  ammonia 
again  added  in  slight  excess.  If  any  precipitate  now 
fall,  it  will  consist  only  of  alumina  and  oxide  of  iron, 
unless  magnesia  and  oxide  of  manganese  be  present  in 
large  proportion,  when  a  minute  quantity  of  each  may 
fall  at  the  same  time. 

The  precipitate  is  to  be  collected  on  the  filter  as 
quickly  as  possible — the  funnel  being  at  the  same  time 
covered  with  a  plate  of  glass,  to  prevent  the  access  of  the 
air — washed  with  hot  distilled  water,  and  then  re-dissolved 
in  muriatic  acid.  This  is  best  effected  by  spreading  out 
the  filter  in  a  small  porcelain  dish,  adding  dilute  acid  till 
all  is  dissolved,  and  then  washing  the  paper  well  with  dis- 
tilled water.  A  few  drops  of  nitric  acid  are  then  to  be 
added,  and  the  solution  heated,  to  convert  the  whole  of 
the  iron  into  peroxide.  A  solution  of  caustic  potash  added 
in  excess  will  at  first  throw  down  both  the  oxide  of  iron  and 
the  alumina,  but  will  afterwards  re-dissolve  the  alumina, 
and  leave  only  the  oxide  of  iron.  A  gentle  heat  will  assist 
this  process.  The  oxide  of  iron  is  to  be  collected  on  a 
filter, washed,  dried,  heated  to  redness,and  weighed.  Every 
JOO  grains  of  this  peroxide  are  equal  to  90  grains  of 
3 


34  ESTIMATION   OF   THE   SALINE   MATTERS. 

protoxide,  in  which  state  the  iron  had  most  probably 
existed  in  the  original  watery  solution  from  the  soil. 

35°.  Estimation  of  the  alumina. — To  the  potash  solution 
muriatic  acid  is  added  till  the  alkali  is  saturated,  or  till 
the  solution  reddens  litmus  paper,*  when  the  addition  of 
ammonia  precipitates  the  alumina  ;  or  a  solution  of  sal- 
ammoniac  may  be  added  to  the  potash  solution  till  the 
alumina  falls.  As  it  is  difficult  to  wash  this  precipitate 
perfectly  free  from  potash,  it  is  better,  after  collecting  it 
on  the  filter,  to  dissolve  it  off  again  by  means  of  dilute 
muriatic  acid,  and  to  re-precipitate  it  by  caustic  ammonia. 
When  well  washed,  dried,  and  weighed,  this  precipitate 
gives  the  true  quantity  of  alumina  present  in  the  solution, 
or  in  the  portion  of  saline  matter  submitted  to  analysis. 

36°.  Estimation  of  the  oxide  of  manganese. — To  the 
ammoniacal  solutions  from  which  the  oxalate  of  lime  has 
been  precipitated  (33°),  a  solution  of  hydro-sulphuret  of 
ammonia  is  to  be  added.  The  manganese  will  fall  in  the 
form  of  a  flesh-red  sulphuret.  When  this  precipitate  has 
fully  subsided,  it  must  be  collected  on  the  filter  and 
washed  with  water  containing  a  very  little  hydro- 
sulphuret  of  ammonia.  The  filter  is  then  put  into  a 
glass  or  porcelain  basin,  the  precipitate  dissolved  off  by 
dilute  muriatic  acid,  and  the  solution  warmed  and  filter- 
ed, if  necessary.  A  solution  of  carbonate  of  soda  then 
throws  down  carbonate  of  manganese,  which  is  collected, 

*  Litmus  paper  is  paper  stained  by  dipping  it  in  a  solution  of  litmus,  a  vege- 
table blue  colour,  prepared  and  »old  for  the  purpose  of  detecting  the  presence  of 
free  acids,  by  which  it  is  reddened;  or  of  free  alkalies,  by  which,  after  being 
reddened  by  an  acid,  the  blue  colour  is  restored. 


ESTIMATION   OF   THE   SALINE   MATTERS.  35 

dried,  and  heated  strongly  to  redness  in  the  air.  Of  the 
brown  powder  obtained,  every  100  grains  indicate  the 
presence  of  93.03  grains  of  protoxide  of  manganese  in  the 
salt  or  solution  under  examination. 

It  will  only  be  in  rare  cases  that  alumina,  or  the  oxides 
of  iron  or  manganese,  will  be  found  in  sensible  quan- 
tity in  the  watery  extract  of  a  soil.  Sulphate  of  iron 
and  sulphate  of  alumina  do  sometimes  occur,  however,  in 
the  soil,  and  to  these  unfrequent  cases  the  processes  above 
described  are  intended  to  apply.  Of  course  they  instruct 
the  reader  also  how  to  separate  iron,  alumina,  and  man- 
ganese from  mineral  waters  or  any  other  sah'ne  solutions. 

37°.  Estimation  of  the  magnesia. — a.  If  no  potash  or  soda 
be  present  in  the  residual  solution  after  separating  the 
manganese,  the  determination' of  the  magnesia  is  easy. 
A  few  drops  of  muriatic  acid  are  added,  and  the  whole 
gently  heated,  and  afterwards  filtered,  to  separate  the 
sulphur  of  the  excess  of  hydro-sulphuret  of  ammonia  pre- 
viously added.  The  solution  is  then  evaporated  to  dry- 
ness,  and  the  dry  mass  heated  slowly  to  dull  redness,  to 
drive  off  all  the  ammoniacal  salts.  A  few  drops  of  diluted 
sulphuric  acid  are  added  to  what  remains,  to  change  the 
whole  of  the  magnesia  into  sulphate,  the  mass  again 
heated  to  redness,  and  weighed.  One  hundred  grains  of 
this  sulphate  indicate  the  presence  of  33.33  grains  of  pure 
magnesia. 

6.  Or  after  filtration,  as  above,  to  separate  the  sulphur 
ammonia  is  again  added  in  excess,  and  then  a  solution  of 
phosphate  of  soda.  Ammoniacal  phosphate  of  magnesia 
falls  which  is  collected  on  the  filter,  washed  with  water 


36  ESTIMATION    OF    THE    SALINE    MATTERS. 

containing  a  little  ammonia,  dried  and  heated  to  redness, 
and  weighed.  Every  100  grains  contain  35.94  of 
magnesia. 

This  is  the  converse  of  the  process  described  in  40°  c. 

c.  But  if  potash   or  soda   be  present — the  weight  of 
which  it  is  desirable  also  to  determine — the  mode  of  sepa- 
rating the  magnesia  will  vary  according  as  the  solution 
contains  or  is  free  from  sulphuric  acid. 

If  it  contain  no  sulphuric  acid,  the  dry  mass,  after 
heating  to  dull  redness,  is  treated  with  a  little  water 
which  dissolves  it  all  except  a  little  magnesia,  which  need 
not  be  separated.  A  quantity  of  red  oxide  of  mercury — 
previously  reduced  to  an  exceedingly  fine  powder,  by  rub- 
bing in  a  mortar  with  water — is  then  to  be  added,  well 
mixed — the  mixture  evaporated  to  dry  ness,  and  then 
heated  to  redness.  Water  now  dissolves  out  the  potash 
and  soda  only,  and  leaves  the  magnesia.  This  is  to  be 
collected  on  a  filter,  washed — not  with  too  much  water — 
heated  to  redness,  and  weighed. 

d.  Or  another  way  is,  to  prepare  carbonate  of  silver, 
by  precipitating  nitrate  of  silver  with  carbonate  of  am- 
monia  and  washing — then   to  boil   the  solution  of  the 
mixed  chlorides  with  this  carbonate  of  silver  till  the  solu- 
tion becomes  strongly  alkaline.     When  filtered  hot,  only 
magnesia  and  chloride  or  carbonate  of  silver  remain  on 
the  filter.     A  little  dilute  muriatic  acid  poured  upon  the 
washed  filter  dissolves  out  the  whole  of  the  magnesia. 
The  solution  evaporated  nearly  to  dryness,  treated  with  a 
few  drops  of   sulphuric  acid,  then  again  evaporated  to 
dryness  and  heated  to  redness,  gives  the  magnesia  in  the 


ESTIMATION   OF   THE  SALINE    MATTERS.  37 

state  of  sulphate,  of  which  every  100  grains  contain  33.33 
grains  of  magnesia. 

c.  But  if  sulphuric  acid  be  present  along  with  the  mag- 
nesia, potash,  and  soda,  we  dissolve  the  dry  mass  in  water, 
adding  a  little  muriatic  acid,  if  necessary,  to  dissolve  the 
magnesia,  which  may  have  become  insoluble  in  water. 
Ammonia  is  now  poured  in,  in  excess,  and,  if  this  cause  a 
railkiness,  a  little  more  acid,  till  the  addition  of  ammonia, 
again  in  excess,  leaves  the  solution  clear.  Arseniate  of 
ammonia  now  throws  down  the  magnesia,  which,  after 
twelve  hours,  may  be  collected  on  a  filter,  washed  with  cold 
water  which  contains  and  smells  of  ammonia,  and  then 
dried  at  212°  Fahr.  Every  100  grains  of  the  precipitate 
thus  dried  contain  21  grains  (20.97)  of  magnesia.  This 
method  separates  the  magnesia,  but  not  the  sxilphuric 
acid,  from  the  solution. 

f.  Or,  when  sulphuric  acid  is  present,  baryta  water  may 
be  added  to  the  solution,  which  will  precipitate  the  siil- 
phuric  acid  as  sulphate  of  baryta,  and  the  magnesia  at  the 
same  time  as  caustic  magnesia.  It  is  quickly  filtered  and 
washed.  Dilute  sulphuric  acid  then  dissolves  the  mag- 
nesia from  the  filter,  leaving  the  sulphate  of  baryta.  The 
solution  of  magnesia  is  evaporated,  and  the  sulphate  of 
magnesia  determined  as  in  a. 

38°.  ^estimation  of  the  potash  and  soda. — a.  If  no  sul- 
phuric acid  has  been  present,  the  solution  containing  the 
potash  and  soda,  as  left  by  process  37°  c,  is  to  be  eva- 
porated to  dryness,  and  heated  to  dull  redness.  The 
weight  of  the  mass,  which  consists  of  a  mixture  of 
chloride  of  potassium  with  chloride  of  sodium  (common 


38  ESTIMATION  OF   THE  SALINE   MATTERS. 

salt),  is  accurately  determined ;  it  is  then  dissolved  in  a 
small  quantity  of  water,  and  a  solution  of  bi-chloride  of 
platinum  added  to  it  in  sufficient  quantity.  Being  eva- 
porated by  a  very  gentle  heat  nearly  to  dryness,  weak 
alcohol  is  added  which  dissolves  the  chloride  of  sodium 
and  any  excess  of  salt  of  platinum  which  may  be  present . 
The  yellow  powder  is  collected  on  a  weighed  filter,  washed 
well  with  alcohol,  dried  by  a  gentle  heat,  and  weighed  on 
the  filter.  Every  100  grains  indicate  the  presence  of 
19.31  potash,  of  potash,  or  30.56  grains  of  chloride  of 
potassium. 

The  quantity  of  chloride  of  sodium  is  estimated  from 
the  loss.  The  weight  of  the  chloride  of  potassium  above 
found  is  deducted  from  that  of  the  mixed  chlorides  previ- 
ously ascertained  :  the  remainder  is  the  weight  of  the 
chloride  of  sodium.  Every  100  grains  of  chloride  of 
sodium  (common  salt)  are  equivalent  to  53.17  of  soda. 

b.  When  the  magnesia  has  been  separated  by  means 
of  silver,  the  solution,  before  being  evaporated,  is  to  be 
made  slightly  sour  with  muriatic  acid,  that  the  chloride  of 
silver  maybe  thrown  down,  collected  on  a  filter,  and  washed. 
The  filtered  solution  is  then  evaporated  and  treated  as  in  a. 

c.  When  the  magnesia  has  been  separated  by  means  of 
arseniate  of  ammonia,  the  solution  containing  the  alkalies 
is  to  be  evaporated  to  dryness,  and  heated  to  redness  in 
a  porcelain  crucible,  till  fumes  cease  to  be  given  off.   When 
cold,  add  a  little  sal-ammoniac,  and  heat  again.     By  this 
operation  the  excess  of  arsenic  acid  is  wholly  driven  off, 
and,  as  the  fumes  of  this  arsenic  acid  are  poisonous,  care 
must  be  taken  that  they  are  not  inhaled.     The  mixed 
chlorides  of  potassium   and  sodium  remain  as  in  the 


ESTIMATION  OP  THE   SALINE   MATTERS.  39 

method  a,  and  are  to  be  treated  in  the  same  way,  if  no 
sulphuric  acid  is  present.  But  if  sulphuric  acid  is  pre- 
sent, the  mixed  salts  are  dissolved  in  water,  and  the  acid 
precipitated  by  baryta  water,  and  separated  by  filtration, 
as  in  37 /. 

d.  After  the  precipitation  by  baryta,  according  to  this 
method  (37/)  ammonia  and  carbonate  of  ammonia  are 
added  to  the  filtered  solutions  which  are  heated  to  boiling. 
In  this  way  the  excess  of  baryta  is  separated.  The  filtered 
solution  is  then  evaporated  to  drive  off  the  ammonia, 
muriatic  acid  added  to  convert  the  alkalies  into  chlorides, 
and  then  these  mixed  chlorides  separated  as  described 
under  a. 

39°.  Estimation  of  the  ammonia. — a.  If  ammonia  be  pre- 
sent in  the  solution  along  with  potash  and  other  substances, 
the  method  by  which  it  can  be  most  easily  estimated  is  to 
introduce  a  separate  portion  of  the  solution  into  a  large 
tubulated  retort,  to  add  water  until  it  amounts  to  nearly 
an  English  pint  — then  to  introduce  a  quantity  of  caustic 
potash  or  caustic  baryta,  and  to  distil  by  a  gentle  heat 
into  a  close  receiver,  containing  a  little  dilute  muriatic 
acid,  until  fully  one-half  has  passed  over.  Bi-chloride  of 
platinum  is  then  to  be  added  to  the  solution  which  has 
come  over,  previously  rendered  slightly  acid  by  muriatic 
acid,  and  the  whole  is  evaporated  nearly  to  dryness  by  a 
very  gentle  heat.  Dilute  alcohol  is  then  added  to  wash 
out  the  excess  of  the  salt  of  platinum,  and  the  yellow 
powder  is  collected  on  a  filter,  washed  with  spirit,  dried 
by  a  very  gentle  heat  and  weighed.  One  hundred  grains 
indicate  the  presence  of  7.61  grains  of  ammonia. 


40  ESTIMATION   OF    THE   SALINE   MATTERS. 

b.  Or    the  yellow  powder,  without  being  so  carefully 
dried,  may  be  heated  to  redness,  when  only  metallic  pla- 
tinum will  remain.     One  hundred  grains  of  this  metallic- 
platinum  indicate  the  presence  of  17.21  grains  of  am- 
monia. 

c.  Or  the   acid  liquor  in  the  receiver  may  be  eva- 
porated to  dryness  in  a  glass  beaker  over  the  water-bath 
till  it  ceases  to  lose  weight.     The  salt  obtained  is  sal- 
ammoniac,    of   which   every  100  grains  represent  31.8 
grains  of  ammonia.     But  this  method  is  not  so  accurate 
as  the  preceding. 

40°.  Estimation  of  the  2>hospkoric  acid. — The  presence 
of  phosphoric  acid  in  the  solution  being  already  ascertain- 
ed (28°),  its  quantity  may  be  most  easily  estimated  as 
follows :  — 

a.  Dissolve   molybdic   acid  in  ammonia,  and  to  the 
solution  add  pure  nitric  acid  till  the  precipitate  at  first 
formed  again  dissolves.     This  acid  solution  of  molybdate 
of  ammonia  is  the  most  delicate  test  for  phosphoric  acid 
yet  known.    The  substance  to  be  examined  by  it  for  phos- 
phoric acid  may  be  dissolved  in  muriatic  acid,  but  nitric 
acid  is  to  be  preferred.     Or,  if  the  substance  be  already 
in  solution,  as  in  the  watery  extract  of  a  soil,  the  solution, 
as  I  have  already  directed  (28°),  should  be  made  acid  by 
means  of  nitric  acid. 

b.  Evaporate  the  solution  to  be  tested  to  a  small  bulk, 
and  add  to  it  a  large  excess  of  the  solution  of  molybdate 
of  ammonia.    This  is  necessary,  because  the  yellow  preci- 
pitate which  falls  contains  nearly  30  times  as  much  molyb- 
dic acid  as  it  does  of  phosphoric  acid.     It  is  known  that 
enough  of  the  molybdic  has  been  used  when,  before  col- 


ESTIMATION   OF    THE    SALINE    MATTERS.  41 

lecting  the  precipitate  on  a  filter,  a  drop  of  the  super- 
natant liquid  gives,  with  sulphuretted  hydrogen  water,  a 
brown  precipitate  of  sulphuret  of  molybdenum . 

Digest  the  solution  with  the  yellow  precipitate  which 
has  fallen,  for  several  hours,  at  a  gentle  heat ;  collect  the 
precipitate  on  a  filter,  and  wash  it  with  a  fresh  portion  of 
the  same  solution  of  the  molybdate  as  was  employed  to 
throw  it  down.  This  precipitate  on  the  filter  contains  all 
the  phosphoric  acid.  But  to  be  sure  of  this,  the  filtered 
solution  (filtrate)  should  be  set  aside  for  some  time  in  a 
warm  place,  to  see  if  any  farther  precipitate  falls. 

c.  The  yellow  precipitate  upon  the  filter  is  now  to  be 
dissolved,  while  still  moist,  in  solution  of  caustic  ammonia, 
and  washed  well  from  the  filter.    To  this  new  solution  add 
one  of  ammoniacal  sulphate  of  magnesia  as  long  as  a  pre- 
cipitate is  seen  to  fall.     Set  aside  for  twelve  hours  in  the 
cold.     The  ammoniacal  phosphate  of  magnesia  which  has 
fallen  is  in  the  state  of  minute  shining  crystals,  which  can 
be  well  distinguished  by  the  aid  of  a  pocket  microscope. 
It  is  to  be  collected  on  a  filter,  washed  with  water,  with 
which  a  third  or  fourth  part  of  solution  of  ammonia  has 
been  mixed,  dried,  heated  to  redness,  the  filter  burned 
separately,  and  its  ashes  added  to  the  rest.     Deducting 
the  ashes  of  the  filter  (p.  18,  note),  every  hundred  grains 
of  the  phosphate  of  magnesia  thus  obtained  contain  64.06 
grains  of  phosphoric  acid  (note,  p.  74). 

d.  The  ammoniacal  sulphate  of  magnesia  required  in 
this  operation  is  easiest  prepared  by  dissolving  sulphate 
of  magnesia  in  water,  adding  ammonia  to  throw  down  mag- 
nesia, then  muriatic  acid  to  dissolve  it ;  again  ammonia — 
followed  by  muriatic  acid,  sufficient,  on  shaking,  to  make 


42  ESTIMATION  OF   THE   SALINE   MATTERS. 

it  clear  again — and  so  on,  till  the  addition  of  ammonia  in 
excess  no  longer  makes  the  solution  milky.  The  prepara- 
tion may  be  made  more  quickly  by  adding  at  once  a 
solution  of  sal-ammoniac*  sufficient  to  prevent  ammonia 
from  throwing  down  the  magnesia  ;  but  in  this  way  the 
young  manipulator  is  more  likely  to  add  an  excess  of 
sal-ammoniac,  which  is  to  be  avoided. 

The  process  above  described  is  excellent  for  determin- 
ing small  quantities  of  phosphoric  acid,  such  as  occur  in  a 
soil.  The  quantity  of  molybdic  acid  required,  in  propor- 
tion to  the  phosphoric  acid,  is  so  great,  however,  that  when 
larger  quantities  of  phosphoric  acid  are  to  be  determined, 
it  is  usual  to  employ  other  methods,  which  need  not  be 
here  described. 

Note  on  the  examination- of  waters. — It  may  be  of  use  to 
some  of  my  younger  readers,  if  I  here  remark  that  natu- 
ral waters  are  examined  in  the  same  way  as  the  watery 
solution  of  a  soil.  The  methods  described  in  the  two  pre- 
ceding chapters  for  the  qualitative  and  quantitative 
examination  and  analysis  of  an  artificially  prepared  solu- 
tion, will  enable  the  young  experimenter  to  arrive  at 
satisfactory  results  in  regard  to  all  but  a  few  of  the  more 
rare  natural  solutions  which  form  our  springs.  The  ochrey 
or  calcareous  deposits  which  sometimes  fall  from  them, 
either  when  exposed  to  the  air,  or  when  they  are  boiled, 
must  be  treated  like  the  earthy  matter  of  the  soil,  as 
described  in  the  succeeding  chapter. 

*  The  reader  understands  that  the  ammonia  and  muriatic  acid,  successively 
added,  form  sal-ammoniac  in  the  solution  itself. 


CHAPTER  V. 

EA.RTHY     MATTERS    OF    THE    SOIL. 


Matter  insoluble  in  water.— Treatment  with  muriatic  acid ;  testing  of  thig  solu- 
tion.—Estimation  of  the  soluble  silica,  the  sulphuric  acid,  the  iron  as  per- 
oxide, the  alumina,  lime,  magnesia,  oxide  of  manganese,  phosphoric  acid, 
potash  and  soda. — How  to  estimate  the  protoxide  of  iron  and  the  carbonic 
acid  in  a  soil. — Treatment  of  substances  insoluble  in  muriatic  acid. — Heating 
with  sulphuric  acid — Fusion  with  alkaline  carbonates. — Summary  of  the  pre- 
ceding methods. — Note  on  tile  and  fire  clays. 

§  I.   ESTIMATION   OF   THE   SUBSTANCES   SOLUBLE   IN 
MURIATIC  ACID. 


41°.  AN  un weighed  portion  of  the  soil  in  its  natural 
state  has  been  used  for  the  preparation  of  the  watery 
extract  already  examined,  as  described  in  Chapter  III. 
A  part  of  this  same  soil,  after  being  so  extracted  with 
water,  is  to  be  treated  with  muriatic  acid  diluted  with 
one  or  two  waters.  If  bubbles  of  gas  are  seen  to  escape 
from  the  soil  when  the  acid  is  first  added,  the  presence  of 
carbonate  of  lime,  and  in  some  cases  of  carbonate  of 
magnesia,  may  be  inferred.  The  quantity  of  carbo- 
nate may  be  judged  of  by  the  rapidity  and  length  of 
time  during  which  these  bubbles  of  gas  continue  to  be 
given  off. 


44  EAKTHY    MATTERS    OF  THE    SOIL. 

42.°  The  soil  and  acid  thus  mixed  are  to  be  disgested 
on  a  sand  or  water  bath  for  some  hours,  diluted  with 
water  and  the  solution  filtered.  It  is  then  to  be  ex- 
amined qualitatively,  as  described  in  Chapter  III.  Gene- 
rally it  will  be  found  to  contain  silica,  alumina,  oxide  of 
iron,  oxide  of  manganese,  lime,  magnesia,  potash  and  soda, 
with  sulphuric  and  phosphoric  acids.  But  some  of  these 
may  be  absent ;  and  this  it  is  necessary  to  ascertain,  as 
it  will  then  be  unnecessary  in  the  subsequent  analysis 
to  take  any  steps  for  determining  their  quantity.  The 
silica  may  be  sought  for  as  described  in  45°. 

43°.  a.  This  preliminary  examination  being  made,  a 
weighed  portion  of  the  soil,  dried  at  250°  Fahr.,  and 
weighed,  is  first  repeatedly  boiled  in  distilled  water,  as 
described  in  19°,  and  then  covered  over  with  diluted 
muriatic  acid,  and  gently  heated  on  a  water  or  sand 
bath,  with  occasional  stirring  for  twelve  hours.  Water  is 
now  added,  the  whole  well  shaken  or  stirred  together,  al- 
lowed to  settle,and  the  solution  poured  off  through  a  filter. 

b.  Over  the  still  undissolved  portion  of  the  soil  strong 
muriatic  acid  may  now  be  poured  so  as  just  to  cover  it, 
and  the  whole  disgested  again,  with  the  aid  of  heat,  for 
several  hours.  Water  is  added,  the  whole  thrown  upon 
the  filter  already  employed  (a),  and  the  insoluble  matter 
washed  till  water  ceases  to  remove  anything,  and  dried  at 
250°  Fahr.,  till  it  ceases  to  lose  weight.  This  weight, 
deducted  from  that  of  the  dry  soil  employed,  indicates 
the  proportion  of  the  washed  soil  which  is  soluble  in  acids. 

From  100  to  400  grains  of  the  dry  soil  may  be  taken 
for  this  treatment  with  acid,  according  as  it  naturally 
contains  more  or  less  sand  and  srravel. 


EARTH1"    MATTERS    OF    THE    SOIL.  45 

44°.  The  dry  insoluble  matter  being  now  heated  to 
redness,  the  organic  matter  burns  away,  and  there  re- 
mains only  the  insoluble  mineral  matter  of  the  soil.  This 
is  to  be  weighed,  and  kept  for  subsequent  treatment  and 
analysis  The  loss,  which  is  organic  matter  insoluble 
in  water  or  acid,  may  probably  serve  as  a  check  upon 
some  of  the  determinations  already  made,  when  examin- 
ing the  soil  in  reference  to  its  organic  matter  only,  as 
described  in  Chapter  II. 

45.°  To  the  mixed  acid  solutions,  43°  a  and  I,  which  will 
probably  be  of  a  reddish-brown  colour,  from  the  presence 
of  peroxide  of  iron,  a  little  nitric  acid  is  to  be  added,  after 
which  they  are  to  be  evaporated  to  dryness  on  the  water- 
bath,  moistened  with  muriatic  acid,  and,  after  standing 
some  time,  treated  with  water.  The  silica  remains  insol- 
uble, and  may  be  collected  on  a  lilter,  washed,  dried, 
heated  to  redness,  and  weighed.  The  weight  indicates 
the  proportion  of  silica  existing  in  the  soil  in  a  state  to 
be  readily  dissolved  by  acids. 

In  less  careful  analysis  of  soils,  this  separation  of  the 
silica  soluble  in  acids,  which  is  rarely  large  in  amount, 
may  be  neglected. 

46°.  The  solution  filtered  from  the  silica  contains  all  the 
ingredients  of  the  soil  which  are  soluble  in  muriatic  acid, 
and  the  nature  and  names  of  which  have  been  already 
determined  (42).  These  ingredients  may  be  separated 
from  each  other,  and  their  several  weights  estimated 
most  readily,  as  follows.  If  all  the  substances  named  in 
42°  have  been  found  in  it,  divide  the  solution  into  four 
equal  parts  by  measure. 

47°.  In  i^G  first,  estimate  the  sulphuric  acid — if  any  be 


46          EARTHY  MATTERS  OF  THE  SOIL. 

present — by  adding  to  it  a  solution  of  nitrate  of  baryta  or 
of  chloride  of  barium,  and  treating  the  precipitate  as  de- 
scribed in  31°.  If  no  sulphuric  acid  be  present,  the  solu- 
tion need  only  be  divided  into  three  parts. 

48°.  In  the  second,  determine  the  phosphoric  acid  by 
means  of  molybdate  of  ammonia,  as  described  in  40°. 
With  this  view,  it  may  be  advantageously  evaporated  to 
dryness,  and  treated  with  concentrated  nitric  acid  aided 
by  heat,  till  the  smell  of  chlorine  passes  off.  It  may  then 
be  dissolved  in  a  little  diluted  nitric  acid  and  added  to 
the  solution  of  molybdic  acid.  Or  the  peroxide  of  iron  and 
alumina  may  be  at  once  precipitated  from  the  solution, 
collected  on  a  filter,  dissolved  while  moist  in  dilute 
nitric  acid,  and  added  to  the  molybdate  of  ammonia.  As 
I  have  already  said,  the  whole  of  the  phosphoric  acid  con- 
tained in  a  soil  almost  invariably  falls  along  with  the  per' 
oxide  of  iron  and  the  alumina. 

49°.     From  the  third  solution  may  be  determined — 

a.  The  lime  and  magnesia,  as  described  in  33°  and 
37°. 

b.  The  peroxide  of  iron,   as  described  in  34°. 

c.  The  alumina,  as  described  in  35°.     The  alumina  ob- 
tained in  this  way  will  contain  also  the  phosphoric  acid. 
But  the  weight  of  the  latter  has  already  been  determined 
in  the  second  portion  of  liquid  (48°),  and  this,  deducted 
from  the  weight  of  the  alumina  here  found,  will  give  the 
true  weight  of  the  alumina. 

In  some  cases  a  portion  of  the  phosphoric  acid  may 
remain  in  the  oxide  of  iron  which  has  been  separated 
from  the  alumina,  but  the  proportion  of  phosphoric  acid 
in  a  soil  is  generally  so  small  that,  in  an  analysis  of  this 


KARTHY  MATTERS  OF  THE  SOIL.          47 

kind,  it  is  rarely  necessary  to  have  recourse  to  further  re- 
fined manipulations  for  the  sake  of  a  theoretical  accuracy 
which  can  lead  to  no  practical  result. 

But  it  may  happen  also  that  the  soil  will  contain  so 
much  phosphoric  acid,  that,  when  ammonia  is  added  to 
the  acid  solution,  a  quantity  of  phosphate  of  lime  or  phos- 
phate of  magnesia,  or  both,  may  fall  along  with  the  iron 
and  alumina.  This  may  be  tested  as  follows  : — 

Dissolve  the  precipitate  in  sulphuric  acid,  add  an  equal 
quantity  of  sulphate  of  ammonia,  making  a  clear  solution 
with  the  smallest  possible  quantity  of  water.  Into  this 
solution  pour  alcohol  in  large  quantity,  shake  well  to- 
gether, and  leave  the  whole  to  settle.  Add  now  a  little 
ether,  and  if  this  troubles  the  solution,  let  it  stand  again 
for  twelve  hours,  then  filter  and  wash  the  precipitate  with 
a  mixture  of  alcohol  and  ether.  Distil  off  the  alcohol 
and  ether,  and  test  the  remaining  solution  for  phosphoric 
acid  by  means  of  ammoniacal  sulphate  of  magnesia,  as 
described  in  40°  c. 

The  precipitate  on  the  filter  will  dissolve  in  water, 
from  which  ammonia  will  throw  down  oxide  of  iron  and 
alumina— oxalate  of  ammonia,  lime,  and  phosphate  of 
soda,  magnesia,  if  any  of  these  are  present. 

If  by  this  testing  the  presence  of  lime  and  magnesia  in 
the  precipitate  from  the  acid  solution  of  the  soil  by 
ammonia,  be  ascertained — the  phosphoric  acid  may  be 
separated  from  it  (the  precipitate),  and  estimated  as 
phosphate  of  magnesia  in  the  way  here  described— the 
iron  and  alumina  as  described  in  34°  and  35°— and  the 
lime  and  magnesia  as  described  in  33°  and  37°. 

d.   The  oxide  of  manganese  may  be  determined  as  de» 


48  KARTHY   MATTERS   OF    THE   SOIL. 

scribed  in  36°,  though  in  ordinary  soil  analysis  the  special 
separation  of  this  oxide  may  be  neglected,  as  it  is  usually 
present  only  in  small  quantity 

e.  Potash  and  soda,  also,  will  only  be  present  in  very 
minute  quantity  in  this  acid  solution,  and  in  most  soil 
analysis  may  be  neglected.  In  this  case  the  magnesia  is 
thrown  down  at  once  by  phosphate  of  soda  (37°  5.)  If  it 
be  desired  accurately  to  estimate  them,  however,  either 
together  or  singly,  it  may  be  done  by  the  methods  de- 
scribed under  38°. 

50°.  From  the  fourth  solution,  the  total  quantity  of  iron 
may  again  be  determined  by  the  measure  method  here- 
after described  under  65°.  Or  if  this  trial,  which  is  very 
brief  and  simple,  be  thought  unnecessary,  the  acid  solu- 
tion may  only  be  divided  into  three  portions  (46°).  There 
is  an  advantage,  however,  in  such  a  double  determination 
by  independent  methods,  as  the  one  result  serves  to  con- 
trol and  test  the  other. 

51°.  Estimation  of  the  protoxide  of  iron  in  the  soil.  It  is 
known  that  there  are  two  oxides  of  iron. 

Iron.  Oxygen, 

The  first  or  protoxide,  consisting  of  £6  16 

The  second  or  peroxide,  or  sesquioxide  56  -j  j 

The  first  of  these,  by  exposure  to  the  air,  soon  changes 
into  the  second.  Nevertheless,  it  frequently  occurs  in 
the  soil,  and  sometimes  materially  affects  its  agricultural 
qualities.  It  is  necessary,  therefore,  in  many  cases,  that 
the  quantity  of  this  protoxide  contained  in  a  soil  should 
be  accurately  estimated.  By  the  process  described  in  34°, 
or  by  the  measure  method  65°,  the  whole  of  the  iron  has 
been  already  obtained  in  the  state  of  peroxide.  The  fol  - 


EARTHY  MATTERS   OF   THE   SOIL.  49 

lowing  method  enables  us  to  determine  how  much  of  this 
existed  in  the  soil  in  the  state  of  protoxide  : — 

A  little  powdered  chalk  or  common  soda  is  introduced 
into  a  flask  with  a  Ujngish  neck,  diluted  muriatic  acid 
poured  upon  it,  and  allowed  to  stand  till  it  has  all  dis- 
solved, and  the  flask  has  become  filled  with  carbonic  acid 
gas.  A  weighed  portion  of  the  dry  soil  is  then  to  be  intro- 
duced into  the  flask,  diluted  muriatic  acid  poured  over  it — 
not  in  too  large  excess — the  flask  lightly  corked,  and  the 
whole  digested  till  the  oxides  of  iron  are  all  dissolved. 
Powdered  carbonate  of  baryta  is  now  to  be  introduced  in 
excess,  and  the  whole  digested  with  the  aid  of  occasional 
shaking.  By  the  action  of  the  baryta,  the'  whole  of  the  per- 
oxide of  iron  and  alumina  will  be  gradually  separated  from 
the  solution,  while  the  protoxide  of  iron  will  remain  dis- 
solved. The  full  production  of  this  effect  will  be  indicated 
by  the  solution  becoming  nearly  colourless,  or  only  of  a 
pale  green.  The  flask  is  now  to  be  filled  with  hot  boiled 
distilled  water,  corked  carefully,  and  the  whole  allowed 
to  settle.  The  solution  is  then  decanted,  or,  if  necessary, 
filtered,  and  the  insoluble  matters  collected  on  the  filter 
and  washed.  The  solution  contains  all  the  iron  which 
existed  in  the  soil  in  the  state  of  protoxide.  It  is  boiled 
with  a  little  nitric  acid  to  convert  it  into  peroxide,  preci- 
pitated by  ammonia,  and  separated  from  alumina,  if  any 
be  still  present,  by  the  method  already  described  in  34°. 
When  dried  and  weighed,  every  100  grains  of  this  perox- 
ide represent  90  grains  of  protoxide  in  the  soil. 

The  weight  of  the  peroxide  thus  obtained,  deducted  from 
that  of  the  whole  peroxide  of  iron  already  determined,  49°b, 
gives  the  weight  of  peroxide  actually  existing  in  the  soil. 
4 


50  EARTHY   MATTERS   OF   THE    SOIL. 

In  this  process  the  flask  is  filled  with  carbonic  acid, 
only  to  prevent  the  protoxide  from  absorbing  oxygen. 
Where  carbonate  of  baryta  cannot  be  obtained,  carbonate 
of  lime  or  chalk  may  be  used  in  its  stead. 

52°.  Estimation  of  the  carbonic  acid  in  the  soil. — When 
lime  and  magnesia  are  present  in  a  soil,  they  are  usually 
combined  for  the  most  part  with  carbonic  acid.  A 
smaller  portion  is  in  combination  with  humic  and  hulmic 
acids,  and  a  portion  probably  also  with  silica.  When  the 
soil  is  treated  with  muriatic  acid,  these  carbonates  of  lime- 
and  magnesia  are  decomposed,  and  their  acid  escapes  in 
the  form  of  carbonic  acid  gas. 

It  is  not  usual,  in  the  analysis  of  a  soil,  to  estimate 
directly  the  weight  of  this  carbonic  acid.  The  lime  and 
magnesia  obtained  in  an  analysis  are  commonly  con- 
sidered to  have  been  altogether  in  the  state  of  carbonates 
in  the  soil — except  what  is  known  to  have  been  in  the 
states  of  sulphate  or  phosphate — and  the  carbonic  acid 
required  to  convert  them  into  carbonates  is  calculated 
and  adopted  as  the/ true  proportion  of  this  acid  contained 
in  the  soil.  This  is  not  strictly  correct,  however  ;  and 
where  rigid  accuracy  is  required,  it  is  necessary  to 
estimate  the  weight  of  the  carbonic  acid  directly.  This 
may  be  done  by  the  following  method  : — 

a.  One  or  two  hundred  grains  of  the  soil,  carefully  dried 
at  212°  to  250°  Fahr.,  are  to  be  introduced  into  a  small 
weighed  flask  or  bottle,  and  then  just  covered  with  a 
weighed  quantity  of  cold  diluted  muriatic  acid.  The 
carbonates  in  the  soil  will  be  gradually  dissolved,  and  the 
carbonic  acid  will  be  set  free  in  the  form  of  gas.  After 
twelve  hours,  or  when  the  action  has  entirely  ceased,  a 


EARTHY  MATTERS  OF  THE  SOIL.          51 

small  tube  is  to  be  introduced  through  the  mouth  of  the 
flask  nearly  to  the  surface  of  the  solution,  and  air  sucked 
through  it  till  the  whole  of  the  carbonic  acid  is  drawn  out 
of  the  flask.  The  flask  with  its  contents  is  now  weighed, 
and  the  loss  of  weight  indicates  the  amount  of  carbonic 
ucid  very  nearly.  Every  100  grains  of  carbonate  of 
lime  in  the  soil  will  lose  in  this  way  44  grains  of  car- 
bonic acid — or  every  100  grains  of  carbonic  acid  indi- 
cate the  presence  of  227.27  grains  of  carbonate  of  lime, 
or  of  127.27  grains  of  lime  in  the  state  of  carbonate. 

b.  This  method  is  not  rigorously  accurate,  since,  on  the 
one  hand,  a  small  loss  of  weight  may  occur  from  the 
escape  of  watery  vapour  carried  off  by  the  gas  or  sucked 
out  by  the  tube  ;  and,  on  the  other,  a  small  gain,  by  the 
retention  of  a  small  quantity  of  carbonic  acid  in  the  solu- 
tion itself.  It  is  made  rigorous  by  passing  the  suction  or 
escape  tube  through  a  well-fitting  cork,  putting  it  into 
the  flask  before  the  commencement  of  the  operation,  and 
weighing  them  together.  The  cork  is  removed  to  intro- 
duce the  materials,  and  immediately  replaced.  A  weighed 
tube,  filled  with  chloride  of  calcicum,*  is  then  attached,  by 
an  India-rubber  joining,f  to  the  escape  tube,  so  that  the  gas 
passes  through  it  and  escapes  dry.  By  heating  the  solution 

*  Chloride  of  calcicum  is  prepared  by  dissolving  lime  in  muriatic  acid,  evapo- 
rating to  dryness,  heating  in  a  crucible  till  it  melts,  pouriag  it  out  upon  a 
cold  flag  or  iron  plate,  breaking  into  pieces,  and,  while  still  hot,  putting  it  into  a 
well-stoppered  bottle.  It  absorbs  moisture  with  great  rapidity,  so  that  if  moist 
air  be  made  to  enter  one  end  of  a  tube  6  or  8  inches  long  filled  with  broken 
pioci's  of  the  chloride,  it  will  escape  at  the  other  end  quite  dry. 

f  Caoutchouc  tubes  of  various  si/.es  are  prepared  and  Hold  for  the  purpose  of 
connecting  pieces  of  apparatus  together.  They  are  recommended  by  their  soft- 
ness (when  gently  warmed),  by  their  elasticity,  and  by  their  power  of  resisting 
the  action  of  acids  and  alkalies. 


52  EARTHY   MATTERS   OF    THE   SOIL. 

at  the  close  of  the  operation,  any  gas  retained  by  the  liquid 
is  also  expelled  ;  and,  by  slightly  loosening  the  cork,  air 
may  be  sucked  through  the  united  tubes  till  all  the  gas 
is  drawn  out  of  the  flask.  The  chloride-of-calcicum  tube 
is  now  detached  and  weighed  separately.  The  increase  of 
its  weight,  if  any,  is  to  be  added  to  that  of  the  flask  and 
suction-tube  weighed  together.* 

§    II. ESTIMATION    OF    THE    SUBSTANCES    INSOLUBLE    IN 

MURIATIC   ACID. 

53°.  The  part  of  the  soil  which  remains  insoluble  in 
muriatic  acid  consists  chiefly  of  quartz  sand,  of  fragments 
of  rock,  and  of  undecomposed  clay  and  other  silictates. 

If  there  be  much  pure  sand  and  fragments  of  undecom- 
posed rock,  these  had  better  be  washed  or  picked  out  and 
weighed  separately.  The  fine  part — or  the  whole  if 
thought  advisable — after  being  reduced  to  fine  powder, 
first  in  a  steel  and  then  in  an  agate  mortar,  may  then  be 
treated  in  one  or  other  of  two  ways. 

54°.  First.  It  may  be  drenched  with  concentrated  sul- 
phuric acid,  and  heated  for  a  considerable  time  in  a 
slightly-covered  platinum  crucible  over  a  lamp,  till  the 
sulphuric  acid  is  nearly  all  driven  off.  When  cold,  it  is 
treated  with  water,  which,  after  being  allowed  to  settle,  is 
filtered.  If,  on  the  addition  of  ammonia  in  excess  to  this 
solution,  a  precipitate  of  alumina  or  of  oxide  of  iron 

*  Various  modifications  of  this  apparatus  are  in  use,  some  more  and  some  less 
complicated.  The  passage  of  another  tube  through  the  cork,  nearly  to  the  bot- 
tom of  the  flask— by  which  the  acid  may  be  poured  in  at  the  beginning,  and  the 
air  enter  at  the  close  of  the  operation— is  an  improvement,  but  what  I  have  de- 
scribed in  the  text  will,  in  careful  hands,  give  very  good  results. 


EARTHY  MATTERS  OF  THE  SOIL.          53 

appears,  the  treatment  with  sulphuric  acid  is  to  be 
repeated  a  second,  and  if  necessary,  a  third  time,  till 
everything  soluble  is  taken  up  by  the  sulphuric  acid. 

By  this  treatment  the  insoluble  silictates  are  decomposed, 
and  only  pure  silica  remains  in  the  crucible  undissolved. 
This  may  be  collected  on  the  filter,  washed,  dried,  heated 
to  redness,  and  weighed.  Its  weight  represents  the  pro- 
portion of  insoluble  silicious  matter  in  the  soil. 

The  solution  in  sulphuric  acid  may  contain  alumina, 
oxide  of  iron,  lime,  and  magnesia.  These  are  to  be  sepa- 
rated, and  their  several  weights  determined  by  the  pro- 
cesses already  described.  Only  in  rare  cases  will  this 
solution  contain  potash  or  soda,  or  phosphoric  acid  ;  but 
if  the  presence  of  these  substances  be  suspected,  they  also 
can  be  sought  for  and  separated  as  described  in  the  pre- 
ceding section. 

55°.  Second. — a.  Or  the  portion  of  soil  on  which  hot 
muriatic  acid  refuses  to  act  may  be  mixed  with  three 
times  its  weight  of  a  mixture  of  carbonate  of  potash  with 
carbonate  of  soda,  in  equal  equivalents,*  and  heated  to 
fusion  in  a  platinum  crucible.  Place  the  crucible  while 
still  hot  on  a  cold  plate,  the  fused  mass  will  then  readily 
separate  from  the  sides  of  the  crucible  as  it  cools,  and  can 
be  easily  taken  out.  The  fused  mass,  along  with  the  cru- 
cible, is  then  put  into  a  beaker  glass,  covered  with  water 

*  That  is,  in  the  proportion  of  69  of  dry  carbonate  of  potash  to  53  of  dry  carbo- 
nate of  soda,  since  these  two  salts  consist  respectively  of — 

Carbonate  of  Potash.  Carbonate  of  SoUa. 

Carbonic  acid,  22.0  Carbonic  acid,  22.0 

Potaah,    .  .      47.2          .  Soda,     .  .  .31.2 

69.2  53.2 

—See  note,  p.  82. 


54  EARTHY   MATTERS  OF   THE   SOIL. 

and  slowly  treated  with  diluted  muriatic  acid,  aided  by  a 
gentle  heat,  as  long  as  anything  is  dissolved.  A  tolerably 
large  vessel  should  be  employed,  that  nothing  may  escape 
during  the  effervescence  that  takes  place.  The  residue  is 
silica,  which  is  to  be  collected  on  a  filter,  washed,  dried, 
and  weighed. 

b.  The  solution  in  muriatic  acid  may  contain  silica, 
alumina,  oxide  of  iron,  lime,  and  magnesia.  A  little  nitric 
acid  being  added,  it  is  to  be  evaporated  to  dry  ness  on  the 
water-bath.  As  it  approaches  to  dryness,  it  should  be 
constantly  stirred,  that  it  may  be  obtained  in  the  form 
of  a  dry  powder.  It  is  then  moistened  with  muriatic 
acid,  after  a  little  treated  with  water,  and  the  silica  which 
remains  undissolved  collected  on  a  filter,  washed,  heated 
to  redness,  and  weighed.  This  weight  is  to  be  added  to 
that  of  the  silica  already  obtained  (a.) 

From  the  acid  solution  the  alumina,  oxide  of  iron,  lime, 
and  magnesia — or  such  of  them  as  are  present — are  to  be  sep- 
arated by  the  processes  described  in  the  preceding  section . 

56°. — a. Potash  and  soda  will  rarely  be  extracted  from  the 
insoluble  part  of  the  soil  by  this  process.  But  if  it  is 
desired  to  seek  for,  or  to  estimate  the  amount  of,  these 
substances  in  the  portion  of  the  soil  left  undissolved  by 
muriatic  acid,  it  must  be  reduced  to  very  fine  powder  and 
intimately  mixed  with  four  or  five  times  its  weight  of 
hydrate  of  baryta,  and  heated  to  incipient  fusion  over  a 
lamp  in  a  silver  crucible.  Platinum  is  slightly  attacked 
by  caustic  baryta.  When  cold,  the  fused  mass  is  treated 
with  diluted  muriatic  acid,  as  ia  56°  a. 

b.  The  silica,  soluble  and  insoluble,  is  then  separated 
as  after  the  fusion  with  potash  and  soda  (55°  b),  and  the 


EARTHY  MATTERS  OF  THE  SOIL.          55 

alumina  and  oxide  of  iron  thrown  down  by  ammonia. 
Sulphuric  acid  is  then  added,  so  as  exactly  to  precipitate 
the  whole  of  the  baryta  held  in  solution,  after  which  the 
lime  is  thrown  down  as  usual  by  ammonia  and  oxalate  of 
ammonia.  Magnesia,  potash,  and  soda,  if  all  present,  are 
now  in  the  solution  in  the  state  of  chlorides,  and  may  be 
separated  by  the  methods  already  described. 

c.  But  if,  in  separating  the  byrata,  an  excess  of  sul- 
phuric acid  has  been  added,  the  solution  containing  the 
magnesia  and  the  alkalies  is  to  be  evaporated  to  dryness, 
and  heated  to  redness,  to  drive  off  the  ammoniacal  salts. 
Dissolved  in  water,  with  the  aid  of  a  few  drops  of  muriatic 
acid,  if  necessary,  a  solution  of  caustic  baryta  is  to  be 
added,  by  which  the  sulphuric  acid  and  the  magnesia  are 
both  thrown  down,  and  may  be  collected  on  a  filter  and 
washed.    Sulphuric  acid  dissolves  out  the  magnesia,  which 
may  be  evaporated  and  estimated  in  the  state  of  sulphate 
of  magnesia,  as  already  described  under  37°/. 

d.  From  the  solution  containing  the  alkalies  the  excess 
of  baryta  is  to  be  thrown  down  as  carbonate,  by  adding 
carbonate  of  ammonia,   and  boiling  (38°  d.)      Filtered 
from  this,  evaporated  to  dryness,  and  heated — a  few  drops  of 
muriatic  acid  being  added,  if  necessary,  to  insure  their  be- 
ing in  the  state  of  chlorides — the  alkalies  are  obtained 
alone,  and  may  be  weighed.    The  potash  is  then  estimated 
by  means  of  bi-chloride  of  platinum,  as  already  described 
under  38°,  and  the  soda  from  the  loss. 

This  process  I  have  thought  it  necessary  to  describe  ; 
but,  as  I  have  already  stated,  it  will  very  rarely  be  neces- 
sary to  test  for,  much  less  to  estimate  quantitatively,  the 


56  EARTHY   MATTERS   OF   THE   SOIL. 

alkaline  matters  contained  in  the  portion  of  a  soil  upon 
which  muriatic  acid  ceases  to  act. 

The  accuracy  and  care  with  which  the  successive  pro- 
cesses have  been  conducted,  is  tested  by  adding  together 
the  weights  of  the  several  substances  that  have  been  sepa- 
rately obtained.  If  this  sum  does  not  differ  more  than 
one  per  cent  from  the  weight  of  the  soil  employed,  the 
results  may  be  considered  to  be  deserving  of  confidence. 
One  of  the  points  in  which  a  beginner  is  most  liable  to 
err  is  in  the  washing  of  the  several  precipitates  he  collects 
upon  his  filters.  As  this  is  a  tedious  operation,  he  is  very 
likely  to  wash  them  at  first  only  imperfectly,  and  thus  to 
have  an  excess  of  weight  when  his  quantifies  are  added 
together — whereas  a  small  loss,  in  a  correct  analysis,  is 
almost  unavoidable.  The  precipitates  should  always  be 
washed  with  distilled  water,  and  till  a  drop  of  what 
passes  through  leaves  no  stain,  when  dried,  upon  a  bit  of 
glass  or  of  bright  platinum  foil. 

§    III.    SUMMARY   OF    THE    PRECEDING    METHODS. 

57°. The  following  scheme  may  be  useful  as  giving  a  brief 
view  of  the  successive  steps  which  are  to  be  taken  in  order 
to  separate  the  several  substances  from  the  solutions  in 
muriatic  acid  by  the  methods  above  described. 

A°.  Digest  the  soil  in  distilled  water,  dry  at  250°  Fahr., 
weigh,  digest  with  dilute  muriatic  acid  for  twelve  hours, 
and  then  with  concentrated  muriatic  acid.  Dilute,  filter, 
and  mix  the  solutions. 

B°.     Add  a  little  nitric   acid,  evaporate  to  dry  ness, 


EARTHY  MATTERS  OP  THE  SOIL. 


moisten  with  muriatic  acid,  treat  with  water,  filter,  and 
then  collect,  wash,  heat  to  redness,  and  weigh  the  silica. 
C°.  Divide  the  solution  into  three  equal  portions. 
a.  In  the  first,  estimate  the  sulphuric  acid  by  means 

of  chloride  of  barium  (31°). 
If.  In  the  second,  estimate  the  phosphoric  acid  by 

molybdate  of  ammonia.  (40°  b). 
c.  Treat  the  third  as  follows-:  It  may  contain 
alumina,  oxide  of  iron,  oxide  of  manganese,  lime, 
magnesia,  potash,  and  soda,  as  well  as  the  sul- 
phuric and  phosphoric  acids  already  estimated 
in  the  other  portions  of  the  solution. 


a.  Add  caustic  ammonia.  The 
precipitate  contains  alumina, 
oxide  of  iron,  phosphoric  acid, 
and  perhaps  some  phosphate  of 
lime  and  phosphate  of  magnesia. 
Collect  on  the  filter,  and  wash. 

6.  Dissolve  the  precipitate  in  a 
small  quantity  of  sulphuric  acid, 
add  a  little  sulphate  of  ammonia, 
and  then  pour  the  solution  into  a 
large  quantity  of  alcohol.  Add 
a  little  ether,  filter,  and  wash  the 
precipitate  with  mixed  alcohol 
and  ether. 

c.  From  the  solution  distil  off 
the  alcohol,  dilute  the  water, 
and  precipitate  the  phosphoric 
acid  by  ammoniacal  sulphate  of 
magnesia  (40Q  c).  Compare  the 
weight  of  this  phosphoric  acid 
with  that  obtained  already  by 
molybdate  of  ammonia  C°  b).  It 
ought  to  be  a  little  less,  as  by  the 
present  process  the  whole  of  the 
phosphoric  acid  is  not  rigorously 
separated. 


d.  Dissolve  in  water  what   re- 
mains on  the  filter  (b) ;  add  cans- 
tic    potash  in  excess,  and  heat 
The  alumina  and  oxide  of  iron 
with  lime  and  magnesia,  if  pre- 
sent,  are    precipitated,    but    the 
alumina   is  re-dissolved.    Filter, 
wash  the  precipitate,  dry,  heat  to 
redness,  and  weigh. 

e.  Dissolve  this  precipitate  in 
muriatic    acid,   throw   down  the 
oxide  of  iron  by  ammonia,  filter, 
wash,  dry,  heat  to  redness,  and 
weigh  the  oxide  of  iron  again. 
If  it  weighs  less  than  the  whole 
precipitate  did,  the  filtered  solu- 
tion contains  lime  or  magnesia. 
Add  it  to  the  solution  from  a. 

/.  To  the  potash  solution  rf  add 
sal-ammoniac,  and  boil  to  precipi- 
tate the  alumina.  Collect  on  a 
filter,  wash,  heat  to  redness,  and 
weigh. 

Note. — If  no  phosphoric  acid  be 
present,  or  if  much  oxide  of  iron 
be  present  along  with  it,  the  pre- 


EARTHY   MATTERS   OF   THE   SOIL. 


cipitate  from  a  by  ammonia  con- 
tains no  lime  or  magnesia,  and 
the  steps  b,  c,  and  e  become  un- 
necessary. 

g.  To  the  ammoniacal  solution 
from  a  (mixed,  if  necessary,  with 
that  from  c),  add  oxalate  of  am- 
monia. Collect,  wash,  heat  to  red- 
ness, and  weigh  the  carbonate  of 
lime  (35). 

/«.  Add  hydrosulphuret  of  am- 
monia to  throw  down  the  manga- 
nese as  sulphuret.  Collect,  dis- 
solve in  muriatic  acid,  precipi- 
tate by  carbonate  of  soda,  collect 
again,  wash,  dry,  heat  to  redness, 
and  weigh  the  oxide  of  manga- 
nese (36°). 

i.  If  no  potash  and  soda  are 
present,  precipitate  the  magne- 
sia by  phosphate  of  soda  (from 
the  filtered  solntion  7i),  collect, 
wash,  dry,  and  weigh  (37°  b).  Or 
evaporate  to  dryness,  add  a  few 
drops  of  sulphuric  acid,  heat  to 
redness,  and  weigh  the  sulphate 
of  magnesia  (37°  a). 

k.  Or  if  the  alkalies  are  present, 
.and  no  sulphuric  acid,  evaporate 
to  dryness,  and  drive  off  all  the 
ammoniacal  salts  by  heat.  Dis- 
solve them  in  a  little  water,  add 
linely-divided  red  oxide  of  mer- 
cury, evaporate  to  dryness,  and 
heat  to  redness.  Water  then  dis- 
solves the  alkalies,  and  leaves  the 


magnesia,  which  is  collected  and 
weighed  (37W  c). 

I.  The  solution  contains  the 
chlorides  of  potassium  and  so- 
dium. Evaporate  to  dryness,  hunt 
to  dull  redness,  and  weigh.  Re- 
dissolve  in  water,  separate  the 
chloride  of  potassium  by  bi-chlo- 
ride  of  platinum,  collect,  dry,  and 
weigh  (38°  o).  The  chloride  of  »n' 
dium  is  estimated  by  the  h><«. 

m.  But  if  sulphuric  acid  1>e  pre- 
sent, precipitate  by  caustic  baryta, 
filter,  and  wash.  Dissolve  the  prct :i- 
pitated  magnesia  from  the  filter  by 
means  of  sulphuric  acid,  evaporate 
to  dryness,  and  estimate  either  as 
sulphate  or  as  phosphate,  (37°  /i. 

«.  To  the  solution  filtered  from 
the  baryta  and  magnesia,  add 
carbonate  of  ammonia,  and  boil. 
Collect  the  carbonate  of  baryta  on 
the  filter,  evaporate  the  solution 
to  dryness,  heat  to  drive  oft'  tin- 
ammoniacal  salts,  add  a  few 
drops  of  muriatic  acid,  and  heat 
again  (38°  d). 

Weigh  now  the  mixed  chlorides, 
and  proceed  as  under  /. 

o.  Finally,  from  the  solution  of 
a  separate  portion  of  the  soil  in 
muriatic  acid,  precipitate  the 
peroxide  of  iron  by  means  of  car- 
bonate of  baryta,  and  then  esti- 
mate the  protoxide  as  described 
under  ,">! '". 


Ifute  on  tile  anil  Jire  clays. — 1  simply  add  here,  in  reference  to  clays  of  every 
kind,  that  they  are  examined  and  analysed  exactly  in  the  same  -way  ss  the  in- 
soluble matter  of  a  soil. 


CHAPTER  VI. 


ANALYSIS   BY    MEASURE — ORES   OF   IRON. 

Estimation  of  substances  by  measure;  principle  on  which  the  method  is  based. 
— Estimation  of  chlorine  in  this  way.— Estimation  of  silver.— Estimation  of 
the  oxides  of  iron  by  measure. — Standard  solution  of  per-manganate  of  pot- 
ash; its  effect  on  the  protoxide  of  iron  ;  mode  of  using  it. — Estimation  of  the 
protoxide  of  iron  in  a  soil. — Estimation  of  the  whole  quantity  of  iron. — 
Analysis  of  the  ores  of  iron. — Estimation  of  the  iron  only,  very  brief  aud 
easy. — Estimation  of  the  other  ingredients  longer  and  more  difficult. 

§   I.   ESTIMATION   OF   SUBSTANCES   BY   MEASURE. 

58°.  BESIDES  the  methods  already  described,  by  which 
the  ingredients  of  a  soil  are  severally  separated,  collected, 
and  directly  weighed,  another  general  method  of  analysis 
exists  by  which  the  separation  and  weighing  of  each  is 
dispensed  with,  and  their  several  quantities  estimated  by 
measure.  This  method,  being  more  speedy,  involving  less 
labour,  and  rendering  the  use  of  the  balance  less  frequent, 
has  recently  come  much  into  favour,  and  is  daily  becoming 
more  improved  and  more  widely  applicable. 

This  method  is  simply  an  extension  of  the  processes  of 
testing  or  qualitative  examination  already  described  in 
Chapter  III.,  and  is  based  upon  the  two  principles — 

1°.  That  the  presence  of  one  known  body,  A,  may  be 
detected  in  a  solution  by  the  visible  change  or  reaction 


60  ANALYSIS  BY   MEASURE— ORES   OF   IRON. 

produced  in  the  liquid  by  the  addition  of  a  solution  of 
another  known  body,  B. 

2°.  That  the  quantity  or  weight  of  the  body  A  may  be 
calculated  from  the  known  quantity  of  the  body  B,  which  it 
is  necessary  to  add  to  the  solution  before  the  visible  change 
or  re-action  ceases  to  be  produced  by  new  additions. 

59°.  And  the  way  in  which  these  principles  are  applied 
to  quantitative  analysis  is  to  prepare  a  standard  solution 
of  the  body  B,  every  cubic  inch  or  other  measure  of  which 
contains  a  known  weight  of  B.  If  of  this  solution  it  be  found 
necessary  to  add  a  known  measure  to  the  solution  A  before 
visible  change  ceases,  then  the  weight  of  B  being  known 
from  the  measure,  the  weight  of  A,  which  is  equivalent  to 
it,  can  be  calculated. 

60°.  Thus  a  solution  of  common  salt  forms  a  white 
visible  curdy  precipitate  when  added  to  a  solution  of 
nitrate  of  silver.  The  curdy  precipitate  is  chloride  of 
silver.  If  the  solution  of  common  salt  be  added  drop  by 
drop,  shaking,  and  allowing  the  whole  to  settle  after  each 
addition,  we  shall  arrive  at  length  at  a  point  when  a  fur- 
ther drop  of  the  salt  solution  will  produce  no  further  pre- 
cipitate. 

Now,  58.46  grains  of  common  salt  (chloride  of  sodium), 
containing  35.46  of  chlorine,  throw  down  exactly  143.46 
grains  of  chloride  of  silver,  containing  also  35.46  grains 
of  chlorine  united  to  10P-  grains  of  silver.*  Or  100  grains 

•  These  two  substances  consist  respectively  of — 

Common  Salt.           Per  cent.             Chloride  of  silver.  Per  cent. 

Chlorine,           35.46  >    of   C  60.663               Chlorine,        35.46  >  Qr   C  24.724 

Sodium,             23.00  >          (39.337              Silrer,          108.00  >  J  75.276 

58.46  100.00  143.46  100.00 


ANALYSIS  BY   MEASURE— ORES   OF  IRON.  61 

of  common  salt  throw  down  245.34  grains  of  chloride  of 
silver,  containing  184.68  of  silver  and  60.66  of  chlorine. 
If,  therefore,  we  dissolve  100  grains  of  pure  common  salt 
in  distilled  water,  and  then  add  water  till  the  solution  fills 
exactly  100  measures  in  our  graduated  tube,  every  mea- 
sure will  represent  1  grain  of  common  salt.  Suppose  now 
we  add  this  solution  (A)  to  that  which  contains  silver  (B), 
till  it  ceases  to  throw  down  anything,  and  that  on  looking 
at  our  graduated  tube  we  find  that  10  measures  of  the 
common  salt  (A)  have  been  required.  These  ten  measures 
contain  10  grains  of  common  salt,  and  represent  14.346 
grains  of  chloride  of  silver,  or  10.797  grains  of  silver, 
which,  without  weighing,  is  the  quantity  of  silver  con- 
tained in  the  solution  B. 

61°.  Or  the  process  may  be  reversed.  The  standard 
solution  (A)  may  in  every  hundred  measures  contain  100 
grains  of  pure  nitrate  of  silver,  and  this  may  be  employed 
exactly  in  the  same  say  to  estimate  the  quantity  of  chlorine 
in  a  solution  B.  Every  100  grains  of  nitrate  of  silver 
throw  down  84.38  grains  of  chloride  of  silver  containing 
25.8  grains  of  chlorine  ;*  so  that  if  exactly  10  measures 
of  the  silver  solution  A.  be  added  to  the  chlorine  or  com- 
mon salt  solution  B,  before  precipitation  ceases,  then  the 
quantity  of  chlorine  contained  in  the  solution  was  exactly 
one-tenth  of  25.8,  or  2.58  grains. 

This  method  may  be  employed,  if  thought  desirable,  in 

•  Nitrate  of  silver  consists  of— 

Per  cent. 

1  Nitrogen,    14.  j  (     8.23 

28.24 


t  i  iMirogen,  i*.  \ 
"•  \  or  \  6  Oxygen,  48.  [ 
UG.  J  (  ,  Silve,.  108. ) 


Nitric  acid. 

Oxide  of  silver,     116.3  i  1  Silver,  '     108.5  I  63.63 

170.  170.  100. 


62  ANALYSIS  BY   MEASURE — ORES   OF  IRON. 

estimating  the  quantity  of  chlorine  in  the  watery  solution 
of  a  soil,  or  in  any  other  solution,  instead  of  the  more 
tedious  one  of  collecting  and  weighing  as  described  in  32°. 

§    II.    ESTIMATION   OF   THE   OXIDES   OP   IRON   BY   MEASURE. 

62°.  The  oxides  of  iron,  and  especially  the  protoxide  of 
iron,  may  be  very  conveniently  estimated  by  measure, 

a.  The  first  step  is  to  prepare  a  standard  solution  of 
pcr-manganate  of  potash.  For  this  purpose  a  portion  of 
the  per-manganate  is  dissolved  in  water  in  a  stoppered 
bottle,  is  allowed  to  settle  till  quite  clear,  and  is  then  de- 
canted carefully,  or  is  at  once  filtered  through  asbestos 
into  another  bottle  which  is  kept  well  closed.  The  solu- 
tion is  of  a  beautiful  violet  colour.  This  solution  has  the 
property  of  imparting  oxygen  to  the  protoxide  of  iron, 
converting  it  into  the  peroxide,  and  at  the  same  time  be- 
coming itself  colourless.  By  adding  a  solution  of  known 
strength,  therefore,  to  one  containing  protoxide  of  iron — 
very  carefully,  and  with  constant  stirring — as  long  as  the 
colour  disappears,  the  quantity  of  the  protoxide  can  br 
calculated. 

63°.  The  next  step,  therefore,  is  to  ascertain  the  strength 
of  the  solution  of  per-manganate  of  potash.  For  this  pur- 
pose 10  grains  of  fine  pianoforte  wire  are  dissolved,  by  the 
aid  of  heat,  in  pure  muriatic  acid  slightly  diluted,  then 
boiled,  and  distilled  water  added  to  raise  the  bulk  of  the 
solution  to  100  measures  of  our  graduated  vessel.  Every 
10  measures  now  contain  1  grain  of  iron — equal  to  1.285 
grains  of  protoxide,  or  1.428  of  peroxide  of  iron. 

To  10  measures  of  this  solution,  containing  one  grain 


ANALYSIS   Br   MEASURE — ORES   OP   IBON.  63 

of  iron  (or  a  larger  quantity  may  be  taken),  add  the  solu- 
tion of  the  per-manganate  till  the  mixture  begins  to 
exhibit  a  pale  red  tint,  which  does  not  disappear  on  stir- 
ring, and  mark  exactly  how  many  measures  of  the  per- 
manganate have  been  employed.  Suppose  20  measures 
have  been  required,  then  we  conclude  that  20  measures 
of  the  solution  are  capable  of  per-oxiding  one  grain  of 
iron  in  the  state  of  protoxide,  and  therefore  indicate  the 
presence  of  1.285  grains  of  protoxide. 

This  testing  should  be  repeated  two  or  three  times,  that 
the  strength  of  the  solution  may  be  accurately  ascertained  ; 
and  it  should  again  be  repeated  at  intervals  when,  after  a 
time,  it  is  again  to  be  employed,  as  the  dissolved  per- 
manganate gradually  decomposes,  and  the  solution  conse- 
quently becomes  weaker. 

64°.  To  estimate  the  quantity  of  protoxide  in  a  soil,  by 
this  method,  is  now  easy.  To  the  solution  of  a  weighed 
quantity  of  the  soil,  prepared  in  an  atmosphere  of  carbonic- 
acid,  as  described  in  51°,  and  diluted  with  Avater,  add  that 
of  the  per-manganate,  till  the  faintest  red  tint  is  visible. 
The  number  of  measures  required  for  this  purpose — the 
strength  of  the  per-manganate  being  known — indicates 
exactly  the  quantity  of  protoxide  of  iron  which  the  solu- 
tion contains. 

65°.  To  estimate  the  peroxide  of  iron  in  the  solution  i.s 
nearly  as  easy.  It  involves,  however,  two  operations. 

«.  To  the  acid  solution  from  the  soil — which  may  or 
may  not  be  prepared  in  an  atmosphere  of  carbonic  acid- — 
add  a  few  small  pieces  of  sheet  zinc,  cork  the  flask  loosely, 
and  heat  to  boiling.  The  zinc  dissolves,  and  the  hydrogen 
given  off  reduces  the  peroxide  of  iron  in  the  solution  to 


64  ANALYSIS  BY  MEASURE — ORES   OF   IRON. 

the  state  of  protoxide.  If  the  solution  be  quite  colourless 
when  all  the  zinc  is  dissolved,  or  only  of  a  pale  green,  the 
de-oxidation  is  complete.  If  it  is  still  brownish,  a  little 
more  zinc  is  added,  and  the  solution  again  heated  to  boil- 
ing. No  zinc  must  be  left  undissolved.  The  whole  of  tin- 
iron  is  now  in  the  state  of  protoxide. 

b.  To  this  solution  add  that  of  the  per-manganate  as 
before,  till  the  pale  red  tint  becomes  visible.  From  the 
measure  employed,  the  whole  quantity  of  iron  in  the  soil 
is  easily  calculated.  And  if  from  this  whole  quantity  we 
deduct  that  which  is  in  the  state  of  protoxide  as  already 
found  (64°),  we  have  the  quantity  which  is  present  in 
the  state  of  peroxide. 

In  making  these  determinations,  greater  accuracy  is 
attained  by  taking  a  bulk  of  pure  distilled  water  equal  to 
that  of  the  mixed  solutions  employed,  and  ascertaining 
by  experiment  how  much  of  the  per-manganate  solution 
is  necessary  to  impart  to  the  water  a  visible  red  tint. 
This  quantity  must  be  deducted  from  that  which  was 
added  to  the  iron  solution,  as  it  was  expended  in  colour- 
ing the  liquid,  and  in  not  per-oxidising  the  iron. 

These  methods  are  much  more  simple  and  expeditious 
than  those  described  in  the  preceding  chapters  (34°  and 
51°),  but  they  are  susceptible  of  great  accuracy.  In  the 
analysis  of  a  soil,  however,  we  can  only  employ  them 
as  auxiliary  processes,  and  to  test  our  other  methods. 
We  cannot  add  the  per-manganate  to  the  acid  solutions 
from-  which  all  the  other  constituents  of  the  soil  are  to  be 
separated,  and  therefore,  in  making  a  somewhat  full  and 
complete  analysis  of  a  soil,  we  must  still  separate  and  esti- 
mate'the  iron  by  the  methods  previously  described. 


ANALYSIS   BY   MEASURE ORES    OF   IROK.  65 


g    III.    ANALYSIS    OF    IRON    ORES. 

66°.  It  is  chiefly  in  the  analysis  of  substances  which 
contain  the  oxides  of  iron  only,  or  in  which  we  desire  to 
estimate  the  quantities  and  proportions  of  the  two  oxides 
of  iron  only,  that  this  method  becomes  of  immediate 
practical  value. 

a.  We  prepare  our  standard  solution  of  per-manganate, 
or  test  it  anew  for  the  occasion. 

b.  We  dissolve  our  iron  ore — say  100  grains — in  muri- 
atic acid  by  the  aid  of  heat ;  dilute,  filter,  and  divide 
into  two  equal  portions. 

c.  Into  the  one  we  pour  the  solution  of  per-manganate 
till  the  visible  lint  appears,  and  from  the  measure  used 
we  calculate  the  quantity  of  protoxide  of  iron. 

d.  Into  the  other,  contained  in  a  flask,  we  introduce  a 
few  pieces  of  zinc,  dissolve  completely  by  the  aid  of  heat — 
satisfying  ourselves,  by  the  disappearance  of  colour,  that 
the  whole  of  the  iron  has  been  changed  into  protoxide. 
We  then  add  per-manganate  of  potash  again,  and  deter- 
mine the  whole  iron  which  the  quantity  of  ore  employed 
(100  grains)  contains. 

The  larger  weight  (from  d)  indicates  the  total  per- 
centage of  iron  which  is  contained  in  the  ore ;  the  smaller 
number  (from  c),  the  per-centage  in  the  state  of  protoxide; 
and  the  smaller,  deducted  from  the  larger,  gives  the  per- 
centage in  the  state  of  peroxide. 

In  iron  ores  the  protoxide  of  iron  very  frequently  exists 
in  the  state  of  carbonate.  It  is  so,  for  the  most  part,  in 
the  clay  iron  ores,  in  the  oolite  ironstone  beds,  and  in  many 
5 


66  ANALYSIS   BY   MEASURE — ORES   OF   IRON. 

others.  In  such  ores,  every  100  grains  of  iron  in  the  state 
of  protoxide  are  equal  to  126  grains  of  carbonate  of  iron.* 

67°.  Where  it  is  not  desired  to  determine  the  propor- 
tions of  the  other  ingredients  of  a  clay  or  other  mixed 
iron  ore,  the  above  method  is  easy,  ready,  and,  in  the 
hands  of  a  good  and  careful  manipulator,  very  accurate. 
It  is  sometimes  desirable,  however,  for  economical  pur- 
poses, to  ascertain  the  proportions  both  of  lime  and  of 
clay  which  an  iron  ore  contains,  and  even  the  proportion 
of  phosphoric  acid.  In  such  cases  the  ore  must  be  dis- 
solved in  muriatic  acid  with  the  aid  of  heat,  and  the 
solution  treated  in  the  same  way  as  if  it  were  the  acid 
solution  yielded  by  a  soil.  And  if  the  insoluble  matter 
of  the  iron  ore  is  also  to  be  analysed,  it  must  be  heated 
with  concentrated  sulphuric  acid,  or  fused  with  the  mixed 
carbonates  of  potash  and  soda,  as  if  it  were  the  insoluble 
matter  of  a  soil,  and  subsequently  treated  exactly  in  the 
same  way  (41°  to  56°). 

Such  an  examination  of  course  involves  both  time  and 
labour. 

*  Thus,  of  pure  metallic  iron — 

100  grains  are  equal  to  128.63  of  protoxide  of  iron. 
100      ...  ...  142.79  of  peroxide  of  iron. 

100      ...  ...  102.85  of  carbonate  of  iron;  and 

100      ...    of  protoxide  to  126.70  of  carbonate  of  iron. 


CHAPTER  VII. 

GENERAL  REMARKS  ON  THE  ANALYSIS  OF  SOILS. 

Tbc  organic  matter,  what  it  practically  suggests. — Soluble  saline  matters ;  quau  tit  T 
of,  in  fertile  soils. — In  what  cases  it  is  necessary  minutely  to  examine  them.— 
Examples  of  Indian  soils. — Soil  from  the  plains  of  Attica. — How  saline  mat- 
ter  is  to  be  removed  from  a  soil. — Matters  soluble  in  muriatic  acid ;  which  of 
them  may  be  neglected. — Insoluble  matter  not  always  necessary  to  be  ana- 
lysed.—How  to  interpret  the  results  of  an  analysis. 

68°.  The  Organic  Matter. — The  estimation  of  the  total 
quantity  of  organic  matter  in  a  soil  throws  light  on  the 
two  practical  questions — hew  much  lime  would  it  be  safe 
to  add  to  it  ?  and  in  what  condition  ought  we  to  add  it  ? 
Where  the  proportion  of  organic  matter  is  large,  large 
doses  of  lime  may  be  applied,  and  it  may  be  in  the  caustic 
state.  Where  the  proportion  is  small,  only  small  doses  of 
caustic  lime  are  usually  admissible,  though  of  unburned 
lime,  chalk,  or  rich  calcareous  marl,  large  applications  may 
be  made. 

Then,  in  regard  to  the  organic  acids,  they  are  generally 
the  cause  of  what  is  called  the  sourness  of  a  soil.  This 
sourness  is  remoyed  by  quicklime  and  by  wood  ashes, 
so  that  the  use  of  these  is  indicated  when  solutions  of  car- 
bonate of  soda  extract  much  humic  and  ulmic  acids  from 
the  soil.  Quicklime  applied  before  rain  soonest  sweetens 


68  GENERAL  REMARKS  ON  THE  ANALYSIS  OF  SOILS. 

the  land,  though  chalk,  or  chalk  marl,  or  shell  sand,  per- 
form the  same  office  somewhat  more  slowly. 

69°.  The  soluble  saline  matter  in  the  soil  is  rarely  verv 
considerable  in  quantity,  and  in  most  cases  it  will  be  suf- 
ficient to  examine  qiialitatively  the  watery  solution  of  a 
soil.  Cases  do  occur,  however — especially  in  low  flat  plains 
which  lie  near  mountain  ranges,  or  the  soil  of  which  is 
rich  in  lime — where  much  saline  matter  exists  in  the  soil, 
and  is  extracted  from  it  by  water.  Such  are  some  of  the 
soils  in  India,  which,  by  washing,  yield  from  1  to  7  per 
cent  of  saline  matter.  Thus  in  several  Indian  soils  exa- 
mined by  the  late  Mr.  Fleming  of  Barochan,  there  were 

contained  in  100  parts — 

1°      2-      :;-      4J      3° 

Carbonate  of  lime,          .  .  Ih      5£      4.J      4        2 

Carbonate  of  magnesia,  .  3$      2          £      1 

Saline  matter  (chlorides,  sulphates, 

and  nitrates,;    .  .  .  1        1J      3J      3       7 

No.  1  was  near  Gya  in  South  Behar.  Never  lies  fal- 
low, is  covered  with  water  during  part  of  the  rainy  season 
— produces  from  30  to  50  bushels  of  wheat  per  acre. 

No.  2.  Same  district.  Not  inundated  by  the  rains — 
produces  wheat,  pease,  cotton,  or  poppy  in  the  dry,  and 
Indian  corn  and  millet  in  the  wet  season.  Sometimes 
manured  with  wood  ashes  and  cow-dung. 

No.  3.  From  North  Behar,  Tirhoot.  Deep  loam, 
yielding  two  crops  yearly.  Not  flooded — 25  to  30  bushels 
of  wheat  per  acre. 

No.  4.  Tirhoot.  Light-coloured  soil,  not  so  produc- 
tive as  No.  3.  Saline  efflorescence  in  patches. 

No.  5.  Tirhoot.  Still  less  productive  ;  nearly  sterile 
in  places  from  saline  efflorescence,  except  in  the  rainy 
season,  when  it  produces  good  crops  of  Indian  corn. 


GENERAL  REMARKS  OX  THE  ANALYSIS  OF  SOILS.  69 

From  these  examples  we  see  that  from  3  to  4  per  cent 
of  saline  matter  may  exist  in  a  soil  in  certain  circum- 
stances, without  rendering  it  unproductive.  More  than 
this,  however,  few  soils  can  contain,  and  vet  continue 
productive.  Where  such  large  quanties  occur,  the  saline 
matter  ought  to  be  washed  out  and  carefully  analysed. 
A  large  proportion,  where  the  soil  continues  fruitful,  will 
usually  prove  to  consist  of  the  nitrates  of  potash,  soda  or 
lime.  In  this  country  as  little  as  1  per  cent  of  common 
salt  has  been  found  to  prevent  crops  from  growing  healthily 
upon  them.  The  fertile  alluvium  of  the  delta  of  Egypt, 
contains,  in  many  places,  upwards  of  one  per  cent  of 
soluble  saline  matter,  but  it  is  not  all  common  salt. 

The  nature  of  the  saline  effloresence  which  forms  upon 
a  soil  is  always  more  or  less  influenced  by  the  nature 
of  the  adjoining  rocks.  Around  Durham,  where  we 
are  in  the  neighborhood  of  magnesian  limestone  rocks, 
sulphate  of  magnesia  is  the  prevailing  incrustation  which 
forms  on  the  soil  in  hot  dry  seasons.  In  some  red  sand- 
stone countries,  gypsum  is  a  frequent  incrustation,  and 
common  salt  in  others  ;  while  at  the  foot  of  granitic  and 
similar  rocks,  alkaline  salts  of  various  kinds  chiefly 
appear. 

The  practical  cure  for  soils  made  barren  by  excess  of 
saline  matter,  is  the  establishment  of  a  thorough  drainage. 
In  showery  countries  these  drains  will  carry  away  the 
excess  of  saline  matter  which  the  rains  will  dissolve  and 
convey  to  them.  In  arid  countries,  the  drain  must  be 
aided  either  by  artificial  irrigation  or  by  yearly  natural 
inundations,  such  as  those  to  which  the  salty  soils  of 
Tirhoot  owe  their  half-yearly  fertility. 


70          GKNKR.VL  REMARKS  OX  THE  AXALTCId  OK  SOILS. 

70°.  I  once  received  a  sample  of  soil  from  the  plains  of 
Atlica,  with  the  information  that  wheat  sown  at  the  close 
of  the  rainy  season  ripened  and  yielded  well,  but  that 
saline  matter  rose  to  the  surface  in  such  abundance  as 
gradually  to  destroy,  or  entirely  burn  up  the  more  ten- 
der grass ;  and  I  was  asked  to  say  how  grass  might  be 
made  to  grow. 

The  soil,  on  analysis,  was  found  to  consist  of — 

Carbonate  of  lime,  .....  33.0H 

Carbonate  of  Magnesia,       .  ...  .  0.7."> 

Sulphate  of  lime,  (gypsum,)  .  .  .  0.18 

Phosphate  of  lime,  .....  0,03.; 

Oxide  of  iron,  .  '    .  .  .  2.91 

Alumina  soluble  in  muriatic  acid,  .  .  2.:;r> 

Organic  matter,        .....  5.75 

Salts  soluble  in  water  (common  salt  and  sulphate  )    A  .,« 
of  soda,)    .....  5    °"° 

Insoluble  silicious  matter  (not  further  analysed,)       50.33 


100.563 

This  soil  was  peculiarly  rich  in  lime,  but  did  not  over- 
abound  in  saline  matter.  It  contained  all  the  elements 
of  a  fertile  soil,  and  its  history  evidently  showed  that  it 
was  the  saline  matter  rising  with  the  water  from  beneath, 
and  left  on  the  surface  as  the  sun  of  the  dry  season  licked 
the  water  up,  which  was  the  cause  of  the  agricultural  evil. 
The  remedy  was  easy.  "  Open  drains,  that  the  water 
which  comes  from  the  mountains  in  the  rainy  season  may 
carry  the  saline  matter  to  the  sea,  instead  of  lodging  in 
and  soaking  the  soil  of  the  plains,  ready  to  parch  the 
sprouting  grass  as  the  dry  season  progresses."  And  a 
similar  remedy  will  cure  all  similar  cases. 

71°.    Matters   soluble   in  muriatic  acid. — From  open, 
oamy,  or  sandy  soils,  it  will  seldom  happen  that,   after 


OKSERAL  RKMARK4  ON  THE  ANALYSIS  OF  SOILS.  71 

boiling  in  water,  any  appreciable  quantity  of  potash  or 
soda  will  be  extracted  by  muriatic  acid.  The  analysis  of 
the  acid  solution  of  these  soils  may  therefore  be  simpli- 
fied by  neglecting  the  estimation  of  the  trace  of  alkaline 
matter  they  may  contain. 

Stiff  clays,  however,  are  more  rich  in  potash  and  soda, 
in  states  of  combination  which  render  them  insoluble  in 
water.  In  the  analysis  of  clay  soils,  therefore,  it  will 
always  be  proper  to  examine  qualitatively  a  portion  of 
the  acid  solution,  and  thus  to  ascertain  if  an  appreciable 
quantity  of  alkali  be  present,  before  deciding  upon  the 
exact  steps  to  be  taken  in  conducting  the  quantitative 
analysis. 

72°.  As  to  the  matter  insohtble  in  muriatic  acid,  an 
ultimate  analysis  of  it  is  only  necessary  in  very  parti- 
cular instances. 

«.  That  which  water  takes  up  represents  the  actually 
soluble  matter  of  the  soil  which  is  ready  at  the  time  to 
minister  to  the  growth  of  plants. 

b.  That  which  is  taken  up  by  muriatic  acid  contains 
those  constituents  of  the  soil  which  are  likely  to  become 
available  to  the  plant  next  in  order,  as  the  carbonic  and 
other  acids  formed  naturally  in  the  soil  continue  to  act 
upon  them. 

c.  That  which  the  muriatic  acid  leaves  undissolved  may 
contain   substances  vahiable  to   plants,  but  they  are  in 
such  a  state  of  combination  as  only  after  a  long  time — or 
after   some   energetic   chemical   treatment,    such  as  the 
application  of  quicklime  or  sulphuric   acid — to   become 
available  to  their  use. 

In  most  cases,  therefore,  the  immediately  and  practi- 


72          GENERAL  REMARKS  ON  THE  ANALYSIS  Of  SOILS. 

cally  valuable  constituents  of  the  soil  may  be  judged  of 
by  a  quantitative  examination  of  the  soluble  parts  of  the 
soil  only. 

73°.  Lastly,  I  would  remark  that  it  is  only  by  bringing- 
a  very  considerable  familiarity  with  practical  agriculture  to 
bear  upon  the  results  of  the  chemical  analysis  of  a  soil, 
that  correct  and  practically  useful  deductions  can  be  drawn 
from  them.  In  every  case,  therefore,  before  finally  inter- 
preting these  results,  we  ought  to  ascertain — 

first,  The  condition  of  the  land  as  to  drainage. 

Second,  The  kind  of  cropping  and  manuring  to  which 
it  has  been  subjected  during  the  preceeding  ten  years. 

Third,  The  peculiarities  of  climate,  if  any,  to  which 
the  soil  or  locality  is  exposed. 

With  the  aid  of  these  practical  elements,  if  he  under- 
stand their  practical  bearing,  good  economical  suggestions 
may  often  be  drawn  by  the  agricultural  chemist  from  an 
accurate  determination  of  the  chemical  composition  of  a 
soil. 


CHAPTER   VIII. 


ANALYSIS   OF   LIMESTONES   AND    MARLS. 


Kstiination  of  the  carbonate  of  liine,  and  of  the  carbonate  of  magnesia. — Com- 
plete analysis  of  a  limestone. — Analysis  of  calcareous  mar'.s. 


§    I.    ANALYSIS    OF    LIMKSTONES. 

74°.  Estimation  of  the  carbonate  of  lime. — In  many 
eases  it  is  sufficient  for  all  economical  purposes  to  deter- 
mine the  proportion  of  carbonate  of  lime  which  a  limestone 
contains.  This  is  very  easily  done. 

a.  The  limestone  is  dissolved  in  dilute  muriatic  acid, 
hastened,  if  necessary,  by  a  gentle  heat.     The  insoluble 
matter  is  collected  on  a  filter,  washed,  heated  to  redness, 
and   weighed.     The  weight   indicates  the  proportion  of 
insoluble  earthy  matter  which  the  limestone  contains,  and 
thus  at  once  shows  whether  it  is  worthy  of  any  further 
examination.     If  so — 

b.  To  the  filtered  solution  caustic  ammonia  is  added, 
and  the  precipitate  collected  and  weighed  as  in  a.     This 
gives  the  proportion  of  soluble  alumina,  oxide  of  iron,  and 
phosphoric  acid,  if  any,  which  the  limestone  contains. 

c.  To   the  filtered  ammoniacal  solution  oxalate  of  am- 
monia is  added  ;  the  oxalate  of  lime  collected,  washed, 


74  ANALTSM   OIT   LIMESTONES    A>*n    MARLS. 

burned,  and  weighed,  as  directed  as  in  33°.  The  weight 
represents  that  of  the  carbonate  of  lime  contained  in  tin- 
portion  of  limestone  employed. 

If  the  three  weights  obtained  from  these  three  opera- 
tions, when  added  together,  make  up  very  nearly  that  of 
the  limestone  employed,  it  may  be  inferred  that  little  else 
is  contained  in  it,  and  the  quality  of  the  limestone  judged 
of  accordingly. 

75°.  Estimation  of  the  carbonate  of  magnesia. — But  the 
deficiency  may  be  considerable,  or  the  limestone  may  be 
suspected  to  contain  magnesia,  the  proportion  of  which  it 
is  desirable  to  ascertain.  In  this  case — 

To  the  solution  filtered  from  the  oxalate  of  lime  we  add 
phosphate  of  soda  as  long  as  a  precipitate  falls,  and  collect 
it  as  described  in  37°  b.  Of  the  phosphate  of  magnesia 
obtained,  every  hundred  grains  represent  seventy-nine 
grains  of  carbonate  of  magnesia  in  the  limstone.* 

76°.  Complete  analysis  of  a  limestone. — For  most  lime- 
stones the  above  examination  is  sufficient.  But  it  is  some- 
times desirable  to  ascertain  the  quantity  of  alkaline  mat- 
ter it  contains — the  phosphoric  acid,  if  any — the  soluble 
silica — and  for  hydraulic  purposes,  the  composition  of  the 
matters  insoluble  in  muriatic  acid.  With  a  view  to  such 
a  complete  analysis  the  following  are  the  steps  : — 

a.  Dissolve  in  dilute  muriatic,  acid,  and  collect  the 
insoluble  matter. 

*  The  phosphate  of  magnesia  obtained- l>y  this  process,  and  the 
carbonate,  are  composed  respectively  of — 

Carbonate.     Per  cent.  Phosphate.    Per  cent 

Magnesia,  20  .|7.fi2        Magnesia,  -10  o5.84 

Carbonic  acid,  2 '2  .~>2.3.s        Phosphoric  acid,  71.4          C4.0<: 

42  100  111.4  100 


ANALYSIS    OF    LIMESTONES    AND    MARLS.  75 

b.  Boil  this  insoluble  matter  in  a  solution  of  carbonate 
of  soda,  collect  on  a  filter,  wash  well,  and  heat  to  redness. 

c.  Treat  this  insoluble  matter  as  if  it  were  the  insoluble- 
matter  of  a  soil.     Heat  it  with  sulphuric  acid,  or  fuse  it 
with  the  mixed  carbonates  of  potash  and  soda,  and  pro- 
ceed to  separate  its  constituents  as  described  in  53°  to  57°. 

d.  Add  muriatic  acid  to  the  soda  solution  b  till  it  is 
distinctly  acid.     Evaporate  to  dryness  on  the  water-bath, 
stirring  towards  the  end  of  the  process.     Drench   with 
muriatic  acid,  treat  with  water,  and  filter.    What  remains 
on  the  filter  is  silica,  soluble  in  carbonate  of  soda.     It  is 
washed,  dried,  heated  to  redness,  and  weighed. 

e.  The  muriatic  acid  solution  a  is  evaporated  to  dry- 
ness  and  treated  as  in  d.     What  remains  on  the  filter  in 
this  case  is  silica,  soluble  in  muriatic  acid. 

f.  The  acid  solution  from  e  is  treated  with  ammonia  in 
excess,    and  the    precipitate,    if  any,    is   collected    and 
weighed.     It  contains  alumina,  oxide  of  iron,  and  phos- 
phoric acid,  if  present,  with  perhaps  a  little  lime  and 
magnesia. 

g.  If  the  precipitate,  while  still  moist,  dissolves  wholly 
in   acetic   acid,  it   contains  no   appreciable   quantity   of 
phosphoric   acid.     The  iron   and  alumina  are  therefore 
separated  by  caustic  potash  in  the  usual  way  (34°,  35°). 

h.  If  it  is  not  wholly  dissolved  by  acetic  acid,  or  if,  for 
other  reasons,  a  further  research  is  thought  necessary,  a 
separate  portion  of  600  grains  of  the  limestone  is  dissolved 
in  muriatic  acid,  and  the  solution  treated  with  ammonia  in 
excess.  A  larger  precipitate  is  thus  obtained,  containing 
a  more  appreciable  quantity  of  phosphoric  acid.  This 
precipitate  is  dissolved  in  nitric  acid,  and  the  phosphoric 


76  ANALYSIS    OF    LIMESTONES    AND    MAKLS. 

acid  separated  by  molybdate  of  ammonia,  and  estimated 
as  described  in  28°  and  40°.  Every  100  of  phosphoric 
acid  obtained  indicate  the  presence  of  217.6  grains  of 
phosphate  of  lime  in  the  limestone.* 

i.  The  ammoniacal  solution  from  f  is  treated  first  with 
oxalate  of  ammonia  to  separate  the  lime,  and  then  with 
phosphate  of  soda  to  separate  the  magnesia,  as  already 
described  (37°  5). 

k.  Potash  and  soda  will  sometimes  be  found  in  a  lime- 
stone ;  but  it  will  very  rarely,  indeed,  be  advisable  to 
seek  for  it  in  the  residual  solution  i.  By  reducing  a  por- 
tion of  the  limestone  to  exceedingly  fine  powder,  and  boil- 
ing with  distilled  water,  any  common  salt,  or  other  soluble 
saline  matter  which  it  may  contain,  will  be  extracted.  By 
evaporating  the  solution  to  dryness,  the  weight  of  this 
may  be  estimated,  and  it  may,  if  necessary,  be  afterwards 
qualitatively  examined,  like  the  watery  extract  of  a  soil 
(19°  to  29°). 

§    II.    ANALYSIS    OF    MARLS. 

77°.  By  a  marl,  or  a  calcareous  marl,  is  generally 
understood  a  clay  or  sand,  which  contains  intermixed  with 
it  a  variable  proportion  of  the  carbonates  of  lime  and 
magnesia,  and  often  a  trace  of  phosphate  of  lime.  The 
mode  of  examining  them  is  nearly  the  same  as  in  the  case 
of  an  impure  limestone. 

*  The  phosphate  of  lime  consists  of — 

Per  cent. 

Lime,  .  .  .        84.0  54.05 

Phosphoric  acid,    .  .        71.4  45.95 

1/55.4  100. 


ANALYSIS   OF    LIMESTONES   AND    MARLS. 


77 


a.  If,  on  adding  muriatic  acid,  bubbles  of  gas  are  given 
off,  it  may  be  inferred  that  carbonate  of  lime  is  present. 
A  weighed  quantity  is  therefore  treated  with  dilute  mu- 
riatic  acid,  the  insoluble  matter  collected  on  the  filter, 
washed,  heated  to  redness,  and  weighed. 

b.  To  the  acid  solution  ammonia  is  added,  the  precipi- 
tate collected,  washed,   and  subsequently  examined  for 
phosphoric  acid,  if  thought  necessary,  as  in  the  case  of 
a  limestone  (76°7i). 

c.  From  the  ammoniacal  solution  the  lime  is  thrown 
down  by  oxalate  of  ammonia,  and  the  magnesia  by  phos- 
phate of  soda,  as  already  described. 

d.  If  it  is  thought  necessary  to  examine  further  the 
matter  insoluble  in  muriatic  acid  (a),  it  is  treated  in  the 
same  way  as  if  it  were  the  insoluble  matter  of  a  soil 
(£3°  to  57°). 


CHAPTER  IX. 


ANALYSIS   OF   SALINE   MANURES. 

Saline  manures. — Common  salt ;  how  it  is  adulterated  and  examined. — Nitrate  of 
soda. — Numerous  adulterations ;  how  to  detect  them. — Sulphate  of  soda  ; 
how  to  test  it. — Sulphate  of  lime,  or  gypsum. — Sulphate  of  ammonia  and 
sal-ammoniac;  mode  of  examining  them. 

78°.  THE  use  of  portable  manures,  either  natural  or 
artificial,  has  now  become  so  very  extended  that  a  simple 
popular  method  of  testing  them  has  become  very  necessary 
both  to  the  dealer  and  to  the  purchaser.  Such  simple 
means  I  shall  endeavor  to  supply  in  the  present  chapter. 

The  portable  manures  at  present  in  use  consist  chiefly 
of  unmixed  saline  manures,  of  preparations  of  bones,  and 
of  natural  and  artificial  guanos.  I  shall  consider  each  of 
these  classes  in  their  order. 

The  saline  manures  which  are  applied  to  the  land  in 
this  country  in  an  unmixed  state  are  common  salt,  nitrate 
of  soda,  sulphate  of  soda,  gypsum,  and  the  sulphate  and 
muriate  of  ammonia  (sal-ammoniac.) 

§    I.    EXAMINATION    OF    COMMON    SALT. 

79°.  Common  salt  is  too  low  in  price  to  admit  of  being 
profitably  adulterated  with  any  other  saline  substance  ex- 


ANALYSIS   OF    SALINE   MANURES.  75) 

cept  gypsum.  But  it  may  be  mixed  with  sand,  or  it  may 
contain,  as  natural  impurities,  traces  of  chloride  of  calcium 
or  chloride  of  magnesium.  To  detect  and  estimate  these — 

a.  It  should  be  put  into  a  hot  oven  in  a  covered  vessel, 
or  dried  in  some  other  way,  at  a  heat  of  300°  Fahr.,  and 
the  loss  of  weight  noted.    This  determines  the  proportion  of 
water  it  contains,  which  in  moist  samples  is  sometimes 
considerable. 

b.  When  thus  dried,  it  should  be  treated  with  water, 
and  the  insoluble  matter  collected,  dried,  weighed,  and 
examined.     This  shows  how  much  earthy  or  other  in- 
soluble impurity  it  contains,  and  a  slight  examination  will 
often  be   sufficient  to    show  what  the  impurity  consists 
of.     Most  of  the  gypsum,  if  any  is  present,  will  remain 
in  this  insoluble  matter. 

c.  Into    a   pint   of  boiling   water  put  an   unweighed 
(quantity  of  the  salt ;  stir  and  add  salt  till  the  water  i.s 

fully  saturated,  and  a  portion  remains  undissolved.  Let 
it  stand  to  settle,  and  then  upon  a  weighed  pound  of  the 
dried  salt,  reduced  to  fine  powder,  pour  the  clear  saturated 
solution ;  stir  and  shake  well.  Set  aside  to  become  clear, 
and  then  pour  the  solution  entirely  off  again.  Dry  the 
salt,  and  weigh  it.  The  loss  shows  the  proportion  of  the 
chlorides  of  calcium  and  magnesium  which  the  salt  con- 
tains. This  operation  is  founded  on  the  fact  that,  after 
water  has  been  fully  saturated  with  common  salt,  it  is  still 
capable  of  dissolving  these  two  chlorides,  and  therefore  of 
extracting  them  from  the  common  salt  with  which  they 
may  be  mixed. 

d.  If  a  more  minute  chemical  examination  be  wished 
for,  the  operator  will  estimate — 


80  ANALYSIS    OF    SALINE     MANURES. 

The  lime  by  oxalate  of  ammonia  (33°).  Every  100 
grains  of  the  carbonate  of  lime  obtained  represent  111 
grains  of  chloride  of  calcium,  or  136  grains  of  dry  sulphate 
of  lime,  or  172  grains  of  common  gypsum  in  the  salt. 

The  magnesia  by  phosphate  of  soda  (37°  6).  Every 
100  of  the  phosphate  of  magnesia  obtained  represent  85.3 
grains  of  chloride  of  magnesium  in  the  salt. 

The  sulphuric  acid  by  chloride  of  barium  (31°).  If  the 
same  solution  be  employed  for  this  purpose  which  has 
been  already  used  for  separating  the  lime  and  magnesia, 
it  must  be  made  distinctly  sour  with  pure  muriatic  acid 
before  the  chloride  of  barium  is  added. 

Every  1 00  grains  of  sulphuric  acid  represent  1 70  grains 
of  anhydrous  or  dried  gypsum  in  the  salt.  From  the 
weight  of  the  lime,  as  estimated  by  the  previous  operation, 
as  much  is  to  be  taken  as  is  required  to  unite  with  this 
sulphuric  acid  to  form  gypsum.  The  remainder  only  of 
the  lime  is  to  be  reckoned  as  chloride  of  calcium.* 

§    II.    EXAMINATION    OF    NITRATE    OF    SODA. 

«.  Nitrate  of  soda  is  often  very  moist.  A  weighed 
quantity,  therefore,  should  be  thoroughly  dried  in  an 
oven  or  otherwise  at  about  300°  Fahr.,  and  the  loss  of 
weight  ascertained.  This  gives  the  proportion  of  water 
it  contains. 

b.  The  dry  salt  may  now  be  treated  with  water,  and 

*  Chloride  of  calcium  consists  of— 

Calcium,         .......  20. 

Chlorine,        .......  35.46 

55.46 


ANALVSIS    OF    SALINE    MAMJKKS 

the  insoluble  matter,  if  any,  collected,  dried,  and  weighed. 
This  gives  the  proportion  of  earthy  or  other  insoluble 
matter  which  it  may  naturally  contain,  or  with  which  it 
may  have  been  artificially  adulterated.  If  the  earthy 
matter  effervesces  when  acid  is  added,  it  consists  in  part 
at  least  of  chalk. 

c.  Of  soluble  salts  the  nitrate  may  contain,  naturallv, 
sulphate  of  soda,  sulphate  of  magnesia,  sulphate  of  lime, 
(gypsum),    and   common   salt.     These   impurities   often 
occur  mixed  with  it  in  the  native  nitre-beds,  but  they 
may  be  added  also  by  way  of  adulteration.     For  the 
latter  purpose,   crystallised  carbonate  of  soda,  which  is 
cheaper  than  the  nitrate,  may  also  be  added. 

d.  When  common  salt  is  thrown  upon  red-hot  coals,  it 
sparkles  or  flies  about  with  a  crackling  noise  (decrepitates). 
Nitrate  of  soda,  and  the  other  salts  above  named,  do  not 
behave  in  this  way.     If  a  decrepitation  take  place,  there- 
fore, when  the  nitrate  of  soda  is  thrown  upon  red  coals, 
the  presence  of  common  salt  may  be  inferred.     Its  quan- 
tity,  at  least,  whether  it  is  great  or  small,  may  also  be 
guessed  at  by  the  quantity  of  this  decrepitation. 

To  estimate  the  exact  amount  of  common  salt  in  the 
nitrate,  however,  a  weighed  quantity  must  be  dissolved 
in  distilled  water,  and  precipitated  by  nitrate  of  silver,  as 
described  in  32°. 

<?.  If  the  addition  of  nifrie  or  muriatic  acid,  or  of  vine- 
gar, to  a  saturated  solution  of  the  nitrate,  causes  bubbles 
of  carbonic  acid  gas  to  appear,  then  it  is  adulterated  with 
carbonate  of  soda.  The  simplest  way  of  determining  how 
much  carbonate  is  present,  is  to  put  a  solution  of  a 

weighed  quantity  of  the  nitrate  into  a  stoppered  bottle 
6 


82  ANALYSIS   OF    SALINE    MANURES. 

to  add  clear  lime  water  as  long  as  a  precipitate  of  car- 
bonate of  lime  falls ;  to  cork  well  up,  shake,  and  allow 
the  white  powder  to  subside.  The  clear  solution  is  then  to 
be  poured  off,  the  bottle  filled  with  boiled  distilled  water, 
and  allowed  again  to  subside.  The  clear  liquor  is  again 
poured  off,  and  the  precipitate  collected  quickly  on  a  filter, 
dried,  heated  to  dull  redness,  and  weighed.  Every  100 
grains  of  this  carbonate  of  lime  represent  133  grains  of 
dry,  or  358  grains  of  crystallised  carbonate  of  soda.* 

/.  To  ascertain  if  it  is  adulterated  with  sulphate  of 
soda  or  sulphate  of  magnesia,  a  hot  solution  of  the  nitrate 
is  to  be  made  slightly  acid  with  nitric  acid,  to  decompose 
any  carbonate  which  may  be  present.  If,  on  the  addition 
of  nitrate  of  baryta,  no  milkiness  appears,  it  contains 
no  sulphate  ;  but  if  it  become  milky,  sulphuric  acid  is 
present. 

If,  on  the  addition  of  lime-water,  a  white  gelatinous 
precipitate  appear,  it  contains  sulphate  of  magnesia,  if 
not  sulphate  of  soda;  and  perhaps  a  little  sulphate  of 
lime  may  also  be  present. 

To  determine  the  quantities  of  these  ingredients;,  a 
weighed  portion  of  the  salt  is  dissolved,  and  the  solution 
divided  into  two  equal  parts. 

From  the  first,  sulphuric  acid  is  thrown  down  by  nitrate 

of  baryta  (31°). 

> 

*  Common  crystallised  carbonate  of  soda  contain-  IM  !•  -s  th;<u  <•'. 
per  cent  of  water,  its  composition  being — 

Soda, L'l.s 

Carbonic  acid,          ....        l."..t 
Water,         .        .        .        .        .        .        (,:'.s 

JOO 
— See  note,  p.  •>'•'•• 


ANALYSIS    OF    SALINE    MANURES.  33 

From  the  second,  lime,  if  present,  by  oxalate  of  am- 
monia (33°),  and  afterwards  magnesia  by  phosphate  of 
soda  (375). 

§  III.  EXAMINATION  OF  CARBONATE  OF  SODA. 

80°.  Crystallised  carbonate  of  soda  is  rarely  adulterated 
in  the  English  market.  It  may  be  more  or  less  purely 
prepared,  however,  containing-  traces  of  common  salt  and 
sulphate  of  soda.  If  a  crystal,  when  heated  to  perfect 
dryness  in  an  oven,  loses  62  per  cent  of  water,  it  may  be 
considered  as  nearly  pure. 

It  is  the  dry  powdery  sodas  of  the  shops  which  arc 
most  subject  to  adulteration.  Dry  sulphate  of  soda  and 
finely-powdered  common  salt  are  the  mixtures  it  usually 
contains.  To  detect  them,  a  hot  concentrated  solution  of 
the  soda  is  treated  with  nitric  acid,  till  all  escape  of  car- 
bonic acid  gas  ceases.  If  much  sulphate  of  soda  be  pre- 
sent, a  strong  solution  of  chloride  of  calcium  (prepared 
by  saturating  muriatic  acid  with  chalk)  will  make  it  milky, 
or  even  thick  with  precipitated  sulphate  of  lime  (gypsum) . 
The  presence  of  common  salt  may  be  detected  by  the 
taste  of  the  dry  carbonate,  and  by  its  crackling  in  the 
tire. 

The  proportion  of  sulphate  may  be  determined  by  ni- 
trate of  baryta  (31°).  Every  100  grains  of  sulphuric 
acid  indicate  178  grains  of  diy,  or  403  grains  of  crys- 
tallised sulphate  of  soda. 

The  proportion  of  common  salt  is  estimated  by  means 
of  nitrate  of  silver  (32°). 


ANALYSIS    OF    SALINE    MAM  RK- 


£    IV.    K.YAMI.XATIOX    OF    SI  Ll'HATE    OF    bolt A 

81°.   Crystallised  sulphate  of  soda  is  rarely  adulterated 
because  of  its  cheapness.     It  consists  of — 

Per  cent. 

Soda :;i.-.!          ]y.p>.") 

Sulphuric   ad<l.       .        .        -10  1'l.vj 

Water,     ....       :MI  .•,:>.»:; 


161. 'J  100. 

so  that,  if  a  crystal,  when  thoroughly  dried,  loses  about 
/>6  per  cent  of  water,  it  maybe  looked  upon  as  practically 
pure. 

The  dry  powdery  sulphate  of  the  shops  usually  contain- 
common  salt  (which  is  still  cheaper),  and  some  times  ;_:\  p 
sum.  By  dissolving  in  the  smallest  possible  quantity  <>f 
water,  the  greater  part  of  the  gypsum  will  remain  behind 
in  the  state  of  a  white  powder,  and  may  be  collected.  If 
much  common  salt  be  present,  it  miy  be  detected  by  th«' 
taste.  Its  exact  quantity  can  only  be  determined  by  rncan^ 
of  nitrate  of  silver  (32°). 

£    V.    EXAMINATION    OF    (.\l'-\   M . 

82°.  Gypsum  is  sold  either  in  the  unburned  or  burned 
state.  The  uuburnecl,  crushed  or  ground  gypsum  is 
rarely  adulterated.  By  washing  with  water,  it  is  easy  to 
ascertain  if  there  are  any  earthy  uncrystalline  substances 
among  it.  When  heated  to  redness,  thi>  crystallised  gyp- 
sum loses  21  per  cent  of  water ;  and  by  this  test  its  free- 
dom from  admixture  may  also  be  judged  of. 


ANALYSIS   .OV   SALINE    MANURES.  85 

(rypsum  in  the  unburned  and  burned  states  consists 
of— 

Unburned  or  Burned 

crystallised.  or  dry. 

Lime,         ™-Vj}fc*i.*,   ,-J'M.i'   28  28 

Sulphuric;  acid,    .,r-v,        «-  •  •  J()  l(l 

Water,        '  .'           .''"'.''    1*  0 

8<i  CS 

Burned  gypsum  crushes  easily,. and  forms  a  fine  white 
powder.  The  only  adulterations  its  price  admits  of  art- 
slaked  lime,  chalk  and  pipe-clay.  If  it  give  off  no  bubbles 
of  gas  when  first  moistened,  and  then  treated  with  an  acid 
it  contains  no  chalk.  If,  when  mixed  and  shaken  up  with 
water,  it  give  a  clear  solution  which  is  not  rendered  milky 
by  blowing  air  through  it  from  the  lungs  for  a  length  of 
time,  it  contains  no  quicklime.  And  if,  when  heated  with 
sulphuric  acid,  and  then  treated  with  water,  it  give  a  so- 
lution from  which'  ammonia  throws  down  no  alumina,  it 
is  not  adulterated  with  clay  (see  54°) 

.'•j  ."lifljaosjiffci-.*  i"i  hlyo*  t-'Ai/!muuuj  I*»  <t.&  ..<*. 

§    VI.    EXAMINATION     OP    SAL-AMMONIAC    AND    StJLtHATE    OF 
AMMONIA. 

83°.  These  salts,  when  pure,  are  colourless — dissolve 
easily  and  without  residue  in  cold  water — when  mixed 
with  slaked  lime,  give  off  a  strong  smell  of  ammonia — 
and  when  heated  over  the  lamp,  entirely  volatilise.  They 
should  therefore — 

First,  be  mixed  with  slaked  lime,  to  ascertain  if  they 
really  contain  ammonia. 

Second,  be  treated  with  water,  and  the  proportion  of 
insoluble  matter,  if  any,  estimated. 

Third,    heated   to  incipient  redness,  till    all   vapours 


86  ANALYSIS   OF    SALINE   MANURES. 

and  smell  cease,  and  the  residue,  if  any,  then  weighed 
and  examined. 

If  the  salt  begin  to  rise  in  vapours  when  heated  to  300° 
or  350°  Fahr.,  and  gradually  disappear  without  melting, 
it  is  sal-ammoniac ;  but  if  it  melt  below  300°  Fahr.  (284), 
and  do  not  begin  to  rise  in  vapour  below  536°  Fahr.,  it  is 
sulphate  of  ammonia. 

By  these  tests  the  two  salts  of  ammonia  can  readily  be 
distinguished.  If  anything  remains  unsiiblimed  on  heat- 
ing to  dull  redness,  it  will  be  sulphate  of  soda,  common 
salt,  or  gypsum.  The  nature  of  this  residue  can  readily 
be  recognised  by  the  rules  already  given. 

The  two  salts  of  ammonia  consist  respectively  of — 

Sal-  Ammoniac.    Percent.  Sulphate  of  Ammonia.    Percent. 

Ammonia,          17.0    or    31.8  Ammonia,  17    or    25.7G 

Muriatic  acid,    3G.4    "     68.2  Sulphuric  acid,  40     "    60.61 

Water,        .  n     "    13.C3 

•>3.l         100 

C(>          100 

So  that  sal-ammoniac,  weight  for  weight,  contains  one-fifth 
more  ammonia  than  the  sulphate  of  ammonia  does. 


CHAPTER  X. 


EXAMINATION     OF   BONE    MANURES,   GUANOS   AND 
OIL-CAKES. 

Crushed  bones. — Dissolved  bones ;  how  to  test  tbem. — Superphosphate  of  lime ; 
different  varieties  of,  how  examined. — Natural  guanos ;  mode  of  examining — 
Artificial  guanos  and  mixed  manures ;  analysis  of.— Examination  of  oil-cake* 
used  as  manures. 

§  I.    EXAINATION    OP   BONES,    CRUSHED  AND    DISSOLVED. 

P-4°.  Crushed  bones,  or  bone  dust,  are  occasionally 
adulterated  with  earthy  admixtures.  The  presence  of 
such  adulterations  may  be  detected— 

First,  By  mixing  with  water,  when  the  lighter  bone 
May  be  washed  off,  leaving  the  heavier  sand  and  earthy 
matter  at  the  bottom. 

Second,  By  burning  a  weighed  portion  in  the  air  at  a 
red  heat,  and  weighing  the  ash  or  residue.  If  the  ash 
exceed  half  the  weight  of  the  bones,  earthy  or  other  matter 
has  been  added  to  them. 

85°.  Dissolved  bones, — By  mixing  crushed  bones  with 
one-third  to  one-half  their  weight  of  commercial  sulphuric 
acid,  they  are  reduced  after  a  time  into  a  pulpy  state. 
When  dried  ly  admixture  with  more  lone  dust,  and  laid 


.'•P.  EXAMINATION  OF  BONE  MANURES  AND  GUANOS. 

in  a  heap  for  some  time,  they  form  an  excellent  prepara- 
tion, which  is  sold  under  the  name  of  dissolved  bones. 

The  above  mode  of  preparation  gives  pure  dissolved 
bones  ;  but  when  manufactured  for  sale  it  is  usual  to  dry 
the  wet  mass  by  mixing  it  with  gypsum,  with  saw-dust, 
charcoal  powder,  dried  peat,  ground  chalk  even,  and 
many  other  comparatively  worthless,  if  not  actually  inju- 
rious, substances. 

Dissolved  bones  ought  to  be  sour  to  the  taste,  and  water 
mixed  with  and  allowed  to  stand  upon  them  should  become 
distinctly  sour.  When  stirred  with  water,  and  the  lighter 
parts  poured  off,  they  ought  to  leave  no  sand  or  other  heavy 
earthy  matter  behind.  The  presence  of  saw  dust,  charcoal, 
peat,  and  other  vegetable  matters,  may  be  ascertained  by 
examining  the  lighter  portions  which  are  washed  off. 

86°.  For  a  more  minute  examination  the  following  steps 
may  be  taken : — 

a.  Heat  a  weighed  portion  to  350°  Falir.  as  long  as  it 
loses  weight.     The  loss  is  water.     Heat  now  to  redness 
in  the  air  till  everything  combustible  is  burned  away,  and 
weigh  again.     The  second  loss  consists  of  vegetable  mat- 
ter, if  any  is  present,  of  the  gelatine  of  the  bones,  and  of 
the  excess  of  sulphuric  acid. 

b.  Digest  the  burned  residue  in  dilute  muriatic  acid  to 
dissolve  the  phosphates ;  filter,  wash,  heat  to  redness,  and 
weigh  the  undissolved  portion.     It  consists  of  gypsum  and 
other  earthy  impurities  which  the  manure  may  contain. 

c.  Boil  this  insoluble  matter  in  a  solution  of  carbonate 
of  soda,  collect  on  the  filter  again,  and  treat  witli  dilute 
muriatic  acid.     If  it  entirely  dissolves  with  effen •'•< ••<•}}>•>•. 
the  insoluble  matter  from  I  has  been  tfvp>um  unlv.     The 


EXAMINATION  OS  BONE  MANURES  AND  GUANOS.  39 

boiling  with  carbonate  of  soda  has  converted  it  into  car- 
bonate of  lime.  If  it  does  not  dissolve  in  dilute  muriatic 
acid  with  effervesence,  it  consists  of  clay  or  other  earthy 
impurities  which  have  been  added  to  the  manure. 

d.  To  the  acid  solution  from  b  add  ammonia  in  excess. 
Collect  the  precipitate,  wash,  dry,  heat  to  redness,  and 
weigh.  It  consists  of  phosphate  of  lime,,  with  a  little 
phosphate  of  magnesia.  Every  100  grains  of  this  precip- 
itate indicate  the  presence  of  aboiit.200  grains  of  bones 
or  bone-dust  in  the  manure.  This  is  the  really  valuable 
ingredient  in  the  manure  ;  and  if  it  has  been  prepared 
from  bones  at  all,  its  worth  may  be  calculated  from  the 
quantity  of  bones  indicated  by  the  weight  of  the  mixed 
phosphates  thus  obtained. 

87°.  The  weight  pf  sulphuric  acid  added  to  the  bones 
by  the  manufacturer  is  not  usually  quite  enough  entirely 
to  decompose  and  render  them  soluble.  But  as  the  imme- 
diate efficacy  of  prepared  bones  as  a  manure  is  very  much 
determined  by  the  proportion  of  them  which  is  so  ren- 
dered soluble,  it  is  desirable  to  ascertain  how  far  this 
effect  has  been  produced  in  the  sample  we  are  examining. 
For  this  purpose — 

a.  A  weighed  quantity  is  to  be  digested  with  the  aid  of 
heat  in  a  large  bulk  of  water — say  500  grains  in  a  pint 
of  water — frequently  stirred,  allowed  to  cool,  <fec.,  and 
finally  filtered. 

b.  Ammonia  is  added  in  excess,  the  phosphate  of  lime 
which  is  thrown  down  collected  on  a  filter,  washed,  heated 
to  redness,  and  weighed.     Every  100  grains  indicate  200 
of  bones  contained  in  the  manure  in  a  soluble  state.    ;  ••'.  : 

<•,  To   the    filtered    solution,    ammoniacal   sulphate  of 


90  EXAMINATION  OF  BONK  MANURES  AND  GUANOS. 

magnesia  is  added  as  long  as  a  precipitate  falls  (40c°). 
The  precipitate,  after  twelve  hours,  is  collected,  dried, 
heated  to  redness,  and  weighed.  Every  100  grains  of 
the  phosphate  of  magnesia  obtained  indicate  the  presence  of 
about  300  grains  of  bones  in  the  manure  in  a  soluble  state. 
The  two  weights  of  bones  indicated  by  b  and  <•  are 
added  together,  and  the  sum  subtracted  from  that  of  the 
whole  weight  of  bones  in  the  manure  (87°rf).  The  re- 
mainder is  the  proportion  of  bone-dust  in  the  manure  which 
is  not  in  a  soluble  or  immediately  available  state. 

§   II.    EXAMINATION   OF  SUPER-PHOSPHATE   OF    LIMK. 

88°.  By  super-phosphate  of  lime  was  meant  at  first 
simply  burned  bones  rendered  soluble  by  means  of  sul- 
phuric acid.  This  is  easily  examined. 

a.  A  weighed  portion  is  boiled  in  water  for  some  time, 
thrown  on  a  filter,  and  washed.     The  solution  contains 
the  soluble  phosphates,  which  may  be  separated  and  esti- 
mated, as  in  86°,  d. 

b.  The  insoluble  matter  on  the  filter  is  now  boiled  for 
tin  hour  in  a  solution  of  carbonate  of  soda.     The  sulphate 
of  lime,  by  this  process,  is  changed  into  carbonate  of  lime. 
This  is  collected  on  a  filter,  washed,  heated  to  redness, 
and  weighed.     If  pure,  or  unmixed  with  sulphate  and 
phosphate,  this  carbonate  of  lime  will  dissolve  with  effer- 
vescence in  dilute  muriatic  acid,  and  will  not  be  precipitated 
again  by  caustic  ammonia  in  excess.     Every  100  grains 
are  equal  to,  or  contain  the  same  quantity  of  lime  as, 
about  200  grains  of  ordinary  bone  dust,*  or  as  1 15  grains 
of  bone-ash. 

*  Or  M  alwut  170  grains  of  cletin,  perfectly  dry  bones. 


EXAMINATION  OF  BONE  MANURES  AND  GUANOS.  91 

c.  But  if  ammonia  throws  down  a  precipitate  from  the 
solution  of  this  carbonate  in  muriatic  acid,  it  is  phosphate 
of  lime,  which  remained  insoluble  in  water  a.  It  is  to  be 
thrown  down  and  collected,  as  in  86°  d. 

The  soluble  phosphate  from  a,  added  to  the  insoluble 
phosphate  from  b,  gives  the  whole  quantity  of  phosphate 
contained  in  the  portion  of  manure  examined. 

89°.  But  by  way  of  improving  this  variety  of  super- 
phosphate, bones  themselves  instead  of  bone-ash  were  after- 
wards dissolved  by  means  of  sulphuric  acid,  and  this 
preparation  was  and  is  still  sold  by  many  under  the  name 
of  super-phosphate.  The  mode  of  examining  this  variety 
lias  been  explained  in  the  preceding  section. 

90°.  3S"ow,  however,  the  commercial  super-phosphates 
are  manufactured  by  dissolving  bones  or  bone-ash  with  a 
variable  proportion  of  powdered  mineral  phosphate  of 
lime,  and  mixing  the  whole  intimately  together.  This 
variety  is  not  so  valuable  as  either  of  the  others  above 
mentioned,  chiefly  because  the  mineral  phosphates  em- 
ployed contain  always  a  large  quantity  of  carbonate  of 
lime  and  of  insoluble  earthy  matter.  Upon  this  lime  much 
of  the  sulphuric  acid  is  wasted  in  converting  it  into  gyp- 
sum, and  the  manure  is  contaminated  with  an  uncertain 
proportion  of  comparatively  useless  ingredients.  The 
samples  brought  into  the  market,  however,  differ  very 
much  in  value,  and  it  may  often  be  desirable  to  test  and 
compare  them. 

A  tolerable  approximation  to  the  value  of  a  sample  may 
be  made  by  boiling  a  weighed  quantity,  as  described 
under  88°,  and  calculating  the  proportion  of  dry  bone-earth 
— the  chief  valuable  ingredient  which  the  manure  contains. 


92  JvXAMINATIOX  OF  r.oXK  MA  NITRES  AND  OTAN' 

For  a  more  detailed  examination,  the  method  given  for 
examining  dissolved  bones  (86°)  may  be  employed. 


III.    EXAMINATION    OK    NATURAL 

91°.  Of  simple  tests  which  can  readily  be  applied  to  a 
natural  guano,  the  three  following  are  within  the  reach  <>t' 
every  one  :  — 

a.  Dry  a  weighed  quantity  at  212°  Fahr.     The  loss  of 
weight  is  water,  and  shows  whether  it  has  been  unduly 
moist.     This   operation  can  be  performed  by  placing  a 
thin  basin  upon  a  pan  of  boiling  water,  spreading  the 
guano  on  the  bottom  of  the  basin,  and  covering  it  with  a 
paper  till  it  has  become  dry. 

b.  Mix  the  guano  with  slaked  lime.     If  a  Mmnu;  smell 
of  ammonia  is  given  off,  it  may  be  presume  d  t<>  he  rich 
in  this  valuable  ingredient. 

c.  Mix  a  quantity  of  the  guano  with  water,  and  stir 
well  ;  allow  it  to  settle  for  a  few  minutes,  and  pour  oil' 
the  lighter  matters  which  still  float  on  the  water.     Repeat 
this  till  all  the  lighter  part  is  washed  away.     It  will  now 
be  seen  if  the  guano  is  mixed  with  much  sand  or  gravel. 
And  if  a  weighed  portion  of  guano  has  been  tlms  washed 
the  sandy  matter  which  remains  can  be  dried  and  weighed, 
and  its  proportion  determined. 

92°.  A  more  thorough  analysis  of  the  gufin<»  is  t<>  !»•• 
performed  as  follows  :  — 

a.  It  is  to  be  dried  at  212°  Fahr.,  and  the  water  deti-r- 
mined  as  before.  From  strong-smelling  guanos  a  little 
ammonia  is  driven  off  by  this  drying,  but  it  rarely  amounts 
19  1  per  cent,  and  can  In-  allowed  for  if  necessary. 


EXAMINATION   OF   BONE    MANURES    AND    GUANOS.         93 

b.  The  dried  guano  is  to  be  heated  to  redness  in  the 
air,    till   everything  combustible    disappears.     The   loss 
consists  of  organic  matters  and  ammoniacal  salts. 

c.  The  burned  residue  is  to  be  treated  with  dilute 
muriatic  acid,  till  everything  soluble  is  taken  up.     The 
insoluble  matter  collected  on  the  filter,  washed,  heated  to 
redness,  and  weighed,  gives  the  proportion  of  useless  gravel, 
sand,  silica,  or  other  matters  which  the  guano  contains. 

Or  this  burned  residue  may  be  washed  first  with  dis- 
tilled water,  to  dissolve  out  the  saline  matter  (//),  and 
then  treated  with  acid  as  here  described. 

d.  Among  these  other  matters,  gypsum,  added  as  an 
adulteration,    may  be  one.      If  this  be  suspected,  the 
insoluble  matter  is  boiled  in  a  solution  of  carbonate  of 
soda,  again  collected  on  a  filter,  and  washed.     If  it  now 
dissolves  with  effervescence  in  muriatic  acid,  it  has  been 
gypsum  ;  if  only  part  of  it  dissolves,  the  insoluble  part 
can  be  washed,  dried,  and  weighed,   and  the  gypsum 
estimated  from  the  loss. 

Or,  if  greater  accuracy  be  desired,  ammonia  may  br 
added  to  this  solution  («?)  in  muriatic  acid,  and  the  limo 
afterwards  precipitated  by  oxalate  of  ammonia,  collected, 
and  heated  to  redness  (33°).  Every  100  grains  of  the 
carbonate  of  lime  obtained  indicate  136  grains  of  burned 
gypsum  in  the  insoluble  matter  from  c,  or  172, grains  of 
common  gypsum  in  the  manure.*  This  method  is  nioro 
accurate,  because  the  carbonate  of  soda  may  have  dissolved 
some  silica  from  the  insoluble  matter,  which  would  propor- 

*  In  the  niauuic  the  gypsum  will  exist  as  common  gjp&um,  uontuintii"  21  per 
pent  of  water;  but  as  obtained  from  r.  it  is  burned  gypsum,  havingbecn  heated  to 
redness. 


94         EXAMINATION    OF   BONE    MANURES    AND    GUANOS. 

tionately  increase  the  apparent  proportion  of  gypsum  if 
calculated  from  the  loss. 

e.  To  the  acid  solution  from  c,  ammonia  is  added  in 
excess.  The  phosphate  of  lime  of  the  guano,  generally 
mixed  with  a  little  phosphate  of  magnesia,  falls.  This 
is  collected  on  a  filter,  washed,  heated  to  redness,  and 
weighed. 

/.  If  carbonate  of  lime  or  chalk  have  been  present  in 
the  guano,  it  is  contained  in  the  filtered  solution  from  e. 
It  is  estimated  by  adding  oxalate  of  ammonia,  and  col- 
lecting and  heating  to  redness  the  oxalate  of  lime  in  the 
usual  manner,  (33°). 

g.  By  now  evaporating  the  filtered  solution  from/,  and 
heating  to  dull  redness  to  drive  off  the  ammoniacal  salts, 
the  saline  or  alkaline  matter  contained  in  the  guano  is 
obtained.  Or  it  may  be  extracted  at  once  by  washing 
the  burned  residue  from  I  with  distilled  water,  and  eva- 
porating the  solution  to  diyness. 

It  will  rarely  be  necessary  to  analyse  this  saline  matter 
further.  It  generally  consists  of  sulphate  of  soda  and 
common  salt,  with  a  trace  of  sulphate  of  potash.  But 
if  it  be  desired  to  determine  the  proportions  of  each,  the 
solution  is  divided  into  three  equal  parts — the  sulphuric 
acid  is  thrown  down  from  one  by  chloride  of  barium(31°), 
the  chlorine  from  another  by  nitrate  of  silver,  and  the 
third  is  treated  with  caustic  baryta,  as  described  in  tho 
summary,  p.  58,  letters  m  and  n. 

h.  If  it  be  desired  to  determine  the  per-centage  of  am- 
monia which  the  guano  contains,  a  weighed  portion  is 
put  in  a  small  retort,  and  covered  with  a  dilute  solution 
of  caustic  potash.  The  retort  is  adapted  to  a  receiver 


EXAMINATION  OF  BONK  MANURES  AND  GUANOS.  95 

containing  a  little  dilute  muriatic  acid,  and  then,  by  the 
aid  of  heat,  the  matter  in  the  retort  is  distilled  to  dryness. 
The  ammonia  which  passes  over  combines  with  the  muri- 
atic acid  in  the  receiver,  and  by  evaporating  the  whole  of 
the  liquid  to  dryness  in  the  water-bath  it  is  obtained  in 
the  state  of  sal-ammoniac.  Every  100  grains  of  this  sal- 
ammoniac  indicate  the  presence  of  31 .8  grains  of  ammonia 
in  the  guano.  (See  also  39°  a.) 

§  IV.    EXAMINATION    OF   ARTIFICIAL    GUANOS    AND    MIXED 
MANURES. 

93°.  Artificial  guanos  have  generally  dissolved  bones 
or  some  variety  of  the  so-called  super-phosphates  for  their 
basis.  To  this  are  added  variable  quantities  of  common 
salt,  sulphate  of  soda,  sulphate  of  magnesia,  sulphate  of 
ammonia,  and,  more  rarely,  nitrate  of  soda.  Useless 
additions  of  gypsum,  burned  clay,  ground  bricks,  ochre, 
tfcc.,  to  give  the  mixture  a  color,  and  to  lower  its  price, 
are  also  made  by  many  manufacturers  of  artificial  manures. 

«.  An  artificial  guano  should  be  subjected  to  the  same 
general  treatment  as  a  natural  guano.  It  may  be  first 
tested  roughly  for  water,  ammonia,  and  sandy  or  earthy 
admixtures,  as  described  under  91°.  If  a  further  exami- 
nation or  analysis  be  thought  necessary,  then  the  water, 
the  organic  matter,  the  sand,  clay,  and  gypsum,  the 
phosphates  and  the  lime,  are  to  be  estimated  as  in  the 
preceding  section  (92°,  a  to  g). 

b.  If  the  soluble  salts  obtained  by  the  procesess  g  have 
been  found,  by  a  preliminary  testing,  to  contain  magnesia, 
this  earth  may  be  separated  by  caustic  baryta,  as  described 


96      EXAMINATION  OF  BONE  MANURES  AND  GUANOS. 

in  37°  c,  and  the  alkalies  afterwards  estimated  cither  sep- 
arately or  together,  as  described  in  38°.* 

c.  The  ammoniacal  salts  are  also  determined  as  in  a 
natural  guano  (92°  h). 

d.  The  nitrates,  if  present,  would  be  destroyed  by  heat- 
ing the  artificial  guano  to  redness.     They  must,  therefore, 
be  extracted  with  water  from  the  guano,  or  mixed  manure 
as  it  comes  to  market.     The  filtered  watery  solution  must 
then  be  tested  for  nitric  acid,  as  described  in  27a.     Then 
i  f  nitric  acid  be  present,  and  the  quantity  of  chlorine  and 
sulphuric  acid  has  already  been  determined,  the  weight  of 
this  acid  is  calculated  from  the  loss. 

§    V.    EXAMINATION    OF    OIL-CAKES, 

The  cake  obtained  from  many  varieties  of  oily  si n!> 
when  crushed  in  the  mill,  is  used  in  England,  and  in  many 
other  countries,  as  a  manure.  It  is  chiefly  rape-cake, 
hemp-cake,  mustard-cake,  cotton-cake,  and  some  others. 
not  much  relished  by  cattle,  which  are  so  employed. 

Linseed,  poppy,  nut,  and  other  sweet  oily  cakes,  which 
are  relished  by  cattle,  and  bring  a  high  price  in  the 
market,  are  frequently  adulterated  with  less  costly  mate- 
rials. Those  which  are  used  as  manures  are  said  to  be  so 
adulterated  also.  Where  such  admixtures  of  cheaper  sub- 
stances are  suspected,  the  following  steps  may  he  taken: — 

1  °.  Reduce  the  cake  to  powder,  and  burn  a  weighed  por- 
tion of  it  in  the  open  air,  till  everything  combustible  bums 
away.  The  ash  should  be  nearly  Avhile,  and  should  not 
exceed  seven  or  eight  per  cent  of  the  weight  of  the  cake. 

*  See  also  Hie  summary  in  i«i;,'e  5**,  uinlcr  Uttn>  1,  in.  :unl  «. 


EXAMINATION  OP  BONE  MANURES  AND  GUANOS.  97 

2°.  Treat  the  ash  with  diluted  muriatic  acid.  It 
should  nearly  all  dissolve,  leaving  no  material  quantity 
of  sand  behind. 

3°.  To  the  filtered  solution  add  ammonia  in  excess, 
when  phosphate  of  lime  will  fall.  Collected,  dried,  and 
heated  to  redness,  the  weight  of  this  phosphate  should  be 
equal  to  three -fifths  of  the  whole  weight  of  the  ash.  If 
it  is  much  less,  some  admixture  may  be  suspected. 

4°.  Reduced  to  powder,  and  treated  with  ether,  a  gen- 
uine oil-cake  will  yield  from  ten  to  twelve  per  cent  of  oil. 
This  may  be  obtained  in  a  separate  state  by  pouring  off 
the  ether  into  a  small  open  glass  vessel,  when  the  ether 
will  evaporate,  and  leave  the  oil  behind. 

5°.  By  breaking  the  cake  into  small  pieces,  treating  with 
repeated  portions  of  boiling  water,  and  then  squeezing  the 
insoluble  remainder  in  a  thin  linen  cloth,  the  husk  of  the 
original  seed  will  be  obtained  in  a  separate  state.  An 
examination  of  this  residue  will  show  whether  any 
foreign  seeds  have  been  mixed  with  the  cake,  what  they 
are,  and  to  what  extent  the  adulteration  has  been  carried. 
It  is  easy  in  this  way,  for  example,  to  detect  the  husks  of 
the  small  and  lighter  coloured  seeds  of  brown,  or,  as  it  is 
commonly  called,  black  mustard. 

6°.  When  mustard-seed  is  crushed  and  mixed  with  cold 
water,  it  emits  the  strong  pungent  smell  for  which  pure 
mustard  is  distinguished.  Rape-seed,  so  crushed  and 
mixed  with  cold  water,  exhibits  also  a  sensible  pungency 
of  smell,  greater  sometimes  than  that  of  mustard-seed,  but 
which  varies  in  strength  with  the  sample  of  rape -seed 
examined.  In  taste,  however,  the  mustard-seed  is  much 
the  stronger. 

7 


98     EXAMINATION  OF  BONE  MANURES  AND  QUANOS. 

Mustard-cake  and  rape-cake,  prepared  by  cold  crushing, 
exhibit  the  same  properties  as  the  seeds  they  are  made 
from.  If  we  suspect  an  adulteration  of  rape  with  mustard 
cake,  therefore,  we  reduce  the  suspected  mixture  to  a  fine 
powder  and  mix  it  with  cold  water.  We  reduce  to  powder 
also  a  sample  of  pure  rape-cake,  and  mix  it  with  water, 
by  way  of  comparison.  The  smell  of  the  pure  rape  will 
probably  be  quite  equal  in  pungency  to  that  of  the  sample 
adulterated  with  mustard ;  but  the  taste  will  be  more 
pungent  in  proportion  to  the  quantity  of  mustard-cake 
present. 

In  this  experiment  boiling  water  must  not  be  used,  as 
that  at  once  destroys,  not  the  pungent  smell,  but  the 
pungent  taste,  both  of  rape  and  of  mustard,  in  the  form 
either  of  seed  or  of  cake. 

The  above  method  of  testing  applies  to  cakus  prepared 
by  cold  crushing ;  but  if,  during  crushing,  either  mustard 
or  rape  seed  be  heated  above  176°  Fah.,  it  no  longer 
gives  the  characteristic  pungent  smell,  when  afterwards 
powdered  and  mixed  with  cold  water.  Most  of  the  rape- 
cake  brought  to  market  has  been  prepared  by  hot  crush  I ny 
the  seeds,  at  a  temperature  often  as  high  as  300°  Fah. 
This  variety  of  cake  emits  very  little  of  the  pungent  smell, 
when  crushed  and  mixed  with  water.  Samples  occasion- 
ally come  into  the  market,  however,  which  have  been 
crushed  in  the  cold  ;  and  as  these  emit  a  powerful  odour, 
they  have  sometimes  been  unjustly  called  adulterated,  and 
been  said  to  contain  quantities  of  black  mustard.  Great 
caution,  therefore,  must  be  exercised  in  coming-  to  such 
conclusions. 


INDEX. 


Absorbing  power  of  the  soil,  13, 14. 

Acid,  sulphuric,  to  test  for  and  estimate, 
24, 31— its  action  on  the  earthy  part  of 
a  soil,  52. 

— —  phosphoric,  how  detected,  29. 

— —  phosphoric,  how  estimated,  40. 

acetic,  as  a  teat,  29. 

free,  detected  oy  litmus.  34. 

molybdlc,  as  a  test  and  re- agent, 

40,46. 

muriatic,  its  use  in  the  analysis  of 

soils,  43. 

carbonic,  estimation  of,  in  the  soil, 

50. 

— —  summary  of  methods  of  analysis 
of,  57. 

Acids,  humic  and  ulmic,  how  to  separate 
from  the  soil,  17. 

crenic,  apocrenic,  jrcif,  and  nitric, 

in  the  soil,  21. 

Air,  how  to  dry,  01. 

Alcohol,  employment  of,  S9. 

Alkaline  matter  in  a  limestone,  76. 

Alumina,  to  detect  and  separate,  25,  34. 
— to  separate  phosphoric  acid  from,47. 

Ammonia  in  the  toil,  to  detect  and  esti- 
mate, 27.  28,  39— salt*  of.  how  to  test 
and  analyse,  85 — arseniate  of,  as  a 
test,  37 — hydrosulphnret  of,  as  a  test, 
34 — molybdate  of,  as  arc-agent,  40. 

Ammoniacal  phosphate  of  magnesia,  41. 

— —  sulphate  of  magnesia  as  a  re-agent, 

Alalysis  of  soils,  uses  of,  8 — how  to  se- 
lect specimens  for,  9— summary  of  the 
methods,  57 — how  Its  results  should 
he  aided  and  interpreted,  72— of  clays, 
>>8 — by  measure  or  volume,  principles 
of,  59— of  limestones,  73 — marls,  76. 

Arseniate  of  ammonia,  as  a  test,  37. 

Arsenic  acid,  its  poisonous  fumes.  38. 

Ash  of  filters,  how  determined,  IS. 

Barium,  chloride  of,  ns  a  test  nnd  re- 
agent, 40. 


Baryta,  caustic,  use  of  for  fusions,  54 — 
water  to  separate  sulphuric  acid,  37 — 
carbonate  of,  as  a  re-agent,  49 — nitrate 
of,  as  a  test,  24. 

Bi-chloride  of  platinum  as  a  test,  27. 

Bones,  crushed  and  dissolved,  how  to 
test  and  analyse.  87. 

Burned  gypsum,  its  properties,  85. 

Caoutchouc  tubes,  use  of,  51. 

Carbonate  of  ammonia  as  a  re-agent,  39 
— of  baryta  as  a  re-agent,  49— of  iron, 
its  composition,  66 — of  lime,  how  de- 
tected in  a  soil,  43 — how  to  estimate 
it,  73 — of  magnesia,  to  estimate  in  a 
limestone,  74— its  composition,  ib  — 
of  potash,  its  composition,  53 — of 
soda,  dry_,  its  composition,  ib, — crys- 
taliscd,  its  composition,  82 — how  to 
detect  it  in  nitrate  of  soda,  31 — of  sil- 
ver, how  prepared,  36 — as  a  test,  ib. 

Carbonic  acid  in  a  soil,  how  to  estimate, 
50. 

Chalk,  o&  a  re-agent,  49. 

Chloride  of  barium  as  a  re-agent,  46 — of 
calcium,  as  a  test  and  re-agent,  28, 83 
— its  composition,  80 — how  prepared, 
61 — used  for  drying  gases,  ib — in 
common  salt,  80— of  magnesium  in 
common  salt,  ib. — of  sodium  in  a  so  - 
1 11 1 ion,  how  estimated,  38 — to  estimate 
it  by  measure,  CO— its  composition,  ib. 
— of  silver,  composition  of.  ib. 

Chlorine,  to  test  for  and  estimate,  25, 3? 
— to  estimate  by  measure,  61. 

Clay  and  oolite  iron  ores  analysed,  65. 

Clays,  tile  and  fire,  how  to  analyse, 
58. 

Common  salt  in  a  solution, how  estima- 
ted, 38— to  estimate  by  measure,  60— 
composition  of,  ib. — its  effect  on  the 
fertility  of  a  soil,  69— how  to  te«t  and 
analyse,  78— how  to  purify,  79— to 
estimate  the  earthy  chlorides  in,  80— 
sulphuric  acid  in,  ib.  , 


100 


IXDEX. 


Constituents  of  a  soil,  their  relation  to 

the  feeding  of  plants,  71. 
Cooling  of  a  soil,  rapidity  of,  15. 
Crushed  bones,  how  to  test  and  anal  vse, 

87. 

Density  of  soils, to  determine,  10. 
Dissolved  bones,  bow  to  test  and  an- 
alyse, 88. 
Drying  power  of  the  soil,  13. 

Ether,  use  of,  47. 

Feeding  of  plants,  relation  of  the  scve- 
eral  constituents  of  a  soil  to  the,  71. 

Filter,  how  to  dry  and  weigh,  18 -ash 
of,  how  determined,  ib. 

Fire  and  tile  clays,  how  to  analyse,  58. 

Fusion  of  soil  with  potash  and  sotto,  53. 
—with  hydrate  of  baryta,  54. 

Gold  dust  as  a  test,  23. 

Grave)  and  sand  in  a  soil,  12. 

Green  vitrol,  as  a  test,  28. 

Guanos,  natural,  to  test  and  analyse,  02 

— adulteration  in,  93— alkaline  matter 

of,  94—  ammonia  in,  95— artificial,  to 

test  and  analyse,  iti. 
Gypsum,  how  to  test  and  analyse,  84— 

composition  of,  burned  and  nnbtirned 

85. 

Heat  absorbed  and  retained  by  a  soil,  14. 
Humic  and  ulmic  acids  of  the  soil,  to 

estimate,  17. 

Hutnus  of  the  soil,  19,21. 
Hydrate  of  baryta,  use  of  for  f  u&iou,  54. 
Hvdrosulphate  of  ammonia  a.s  :i  t«--t 

34. 

India-rubber  tubes,  51. 

Indian  soils,  saline  matter  in,  Or. 

Insoluble  matters  of  a  soil,  45,  52. 

Iron,  peroxide  of,  in  a  soil,  to  estimate, 
33,  43,  63— to  separate  it  from  alumi- 
na, 33— oxide  of,  to  separate  phos- 
phoric acid  from,  47 — protoxide  of,  in 
a  soil  to  estimate,  43,  63— oxides  and 
carbonate  of,  their  composition,  48, 6G 
—oxides  of,  to  estimate  by  measure, 
63  -ores  of,  to  analyse  by  measure,  65 
—carbonate  of,  in  iron  ores,  it. 

Lime,  to  detect  and  separate,  26,  32— 
carbonate  of,  how  to  estimate,  73 — 
superphosphate  of,  12— to  test  for  and 
analyse,  90. 

Limestones,  how  to  analyse,  75— alka- 
line matter  in,  to  estimate,  76, 

Litmus  paper,  how  prepared,  34. 

Magnesia,  to  detect  and  separate,  25,  35 
— to  separate  from  potash  and  soda,  3d 
— to  separate  phosphoric  acid  from, 
47 — sulphate  of,  its  composition,  35— 


carbonate  of,  its  composition,  74 — 
phosphate  of,  its  composition,  tb. 

Manganese,  oxide  of,  to  detect  and  esti- 
mate, 34. 

Manure  cakes,  to  examine,  97. 

Manures,  mixed,  to  test  and  analyse,  95 
— saline,  to  test  and  analyse,  78. 

Marls,  how  to  analyse,  77. 

Measure  analysis,  principles  of,  59. 

Mixed  manures,  to  test  and  analyse,  9,">. 

Molybdate  of  ammonia  as  a  re-agent, 
40,  46. 

Muriatic  acid,  its  use  in  the  analyses  of 
soils,  43. 

Mustard  ssed  and  cake,  to  examine,  97. 

Natural  waters,  how  to  test  and  analyse, 
42. 

NMtrate  of  baryta  as  a  test,  24-  of  silver 
as  a  test,  25 — its  composition,  61 — 
standaid  solution  of  it,  ib.—  of  soda, 
how  to  test  and  analyse,  81— to  detect 
common  salt  in  it,  tft. — adulterations 
of  it,  it.—  to  detect  carbonate  of  soda 
in  it,  ib. 

Nitrates,  how  detected  in  the  soil,  23 
how  detected  in  mixed  manures,  96. 

Nitric  acid  in  the  soil,  how  to  detect  it, 
21,2*.  * 

Oil  cakes  to  test  and  examine,  97. 
Oolite  and  clay  iron  ores,  how  analy  •-«••!, 

65. 

Ores  of  iron,  how  analysed,  65. 
Organic  matter  of  a  soil,  to  determine, 

16  -what  it  practically  suggests,  63. 
Oxalate  of  ammonia  as  a  test,  26.  3-.'. 
Oxides  of  iron,  to  detect  and  estimate, 

33,  48, 63— composition  of,  60. 

Per-manganate  of  potash  as  a  re- agent, 
62— standard  solution  of,  ib. 

Phosphate  of  soda  as  a  test,  35  —of  mag- 
nesia, its  composition,  36,  '4. 

Phosphoric  acid, to  detect  and  estimate, 
29,  40 — to  separate  it  from  allumina, 
magnesia,  and  oxide  of  iron,  47. 

Plants, feeding  of,  relation  to  the  several 
constituents  of  a  soil  to  the,  71. 

Platinum,  bi-ch\ori<!e  of,  as  a  te^:,  27, 
38. 

Totash,  carbonate  of,  ils  composition, 
53 — and  6"da  in  a  soil,  to  detect  and 
estimate  26,  37. 

Precipitates,  to  ascertain  if  they  an- 
completely  washed,  IS. 

Bape  and  mustard  cakes,  to  examine, 
117. 

Pal-ammoniac  as  a  re-agent,  34, 3S.  42 — 
its  composition,  86— how  to  test  and 
analyse,  85—  its  relation  to  heat,  86. 

Saline  manures,  to  te*t  and  analv=e, 
78. 


INDEX. 


101 


Saline  matter  of  the  soil,  24 — ia  Indian 
Boils,  68— in  soils  near  Durham,  69— 
on  the  plains  of  Athens,  70 — in  allu- 
vium of  Egypt,  69. 

Sand  and  gravel  in  a  soil,  12. 

Silica  soluble  in  the  soil,  30,  45— in  a 
soil,  how  determined,  53. 

Silver,  to  estimate  by  measure,  61— car- 
bonate 11  f,  as  a  test,  i!G — nitrate  of,  us 
a  test,  25. 

Slaked  lime,  its  use  as  a  re-agent,  85. 

Soda  in  a  soil,  £7,  38 — carbonates  of, 
their  composition,  53,  Si!— nitrate  of, 
to  test  and  analyse,  80-  carbonate  of, 
to  test  and  analyse,  S3 — sulphate  of, 
to  test  and  analyse,  84— its  composi- 
tion, Of. 

Soils,  why  they  should  be  analysed.  7 — 
proportions  of  lime  and  organic  mat- 
ter in,  what  they  suggest,  8 — fine  sand 
in,  often  resembles  clay,  ib. — oxide  of 
iron  in,  ib.— benefits  of  a  more  reGned 
analysis  of,  9— how  to  select  speci- 
men!! for  analysis,  ib. — physical  prop- 
erties of,  how  determined,  10  —  density 
of,  to  determine,  ib. — absolute  weight 
of,  11 — proportions  of  gravel,  sand  and 
clay  in,  ib.—  power  of  absorbing  and 
retaining  water,  13— rapidity  of  dry- 
ing, zft.— and  of  cooling,  15— power  of 
absorbing  heat  from  the  sun,  14— or- 
ganic matter,  how  determined,  16 — 
hurnic  and  ulmic  acids  of,  17 — insolu- 
ble vegetable  matter  of,  19 — use  of 
alum  in  determining  their  organic 
matters,  ib. — soluble  organic  acids  in, 
21— nitric  acid  in,  how  to  detect,  ib , 
28— saline  matter  of,  24— sulphuric 
acid  of,  ib.,  31— chlorine  of,  25,  38 — 
alumina  of,  25,  34,  55 — magnesia  of, 
25,  35— peroxide  ot  iron  in,  26,  33,  63 
— protoxide  of  iron  in,  48,  63— lime 
of,  26,  32— potash  and  soda  in,  26,  37, 
ammonia  in,  to  detect,  27 — phosphoric 


acid  in,  to  detect  and  estimate,  29,  40 
—soluble  silica  i a,  30,  45 -treatment 
of,  with  muriatic  acid,  43— earthy 
natters  of,  how  examined,  ib.— to  de- 
tect carbonate  of  lime  in,  ib— estima- 
tion of  carbonic  acid  in,  SO—  insoluble 
part,  how  to  fuse  in  potash  and  soda, 
53— with  caustic  baryta,  54-  silica  in, 
how  determined,  53 -organic  matter 
of,  what  it  practically  suggests,  68— 
Indian,  soluble  saline  matter  in,  ib. — 
near  Durham,  saline  efflorescence  in, 
09— from  plains  of  Athens,  composi- 
tion and  qualities  of,  70— of  Egypt, 
fi9— relation  of  their  several  constit- 
uents to  the  feeding  of  plants,  71— 
how  the  results  of  an  analysis  should 
be  interpreted,  72. 

Sulphate  of  ammonia  as  a  re-agent,  47— 
its  composition,  86— how  to  test  and 
analyse  it,  85— its  relations  to  heat, 
86. 

Sulphate  of  iron  in  soils,  35 — of  alumina 
in  soils,  ib,— of  lime  or  gypsum,  how 
to  tost  and  analyse,  85— of  magnesia, 
its  composition,  35— its  use  as  a  re- 
agent, 41. 

Sulphuric  acid,  to  test  for  and  estimate, 
24,  31— to  separate  from  potash,  37. 

Superphosphate  of  lime,  to  test  and  ana- 
lyse, 90. 

Testing,  preliminary,  of  a  soil,  24, 44. 
Tile  and  fire  clays,  how  to  analyse,  58. 

Ulmic  acid  of  the  soil,  17. 

Vegetable  matter  of  the  soil,  19. 
Volumetrical  analysis,  Principles  of,  59. 

Water  absorbed  and  retained  by  a  soil, 

13. 

Waters,  natural,  how  to  examine,  42. 
Weight,  absolute,  of  soils,  11. 


THE  KND. 


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